Exhaust/Muffler

Because the VW is rear engined, front and rear descriptions can easily get mixed up -- it's normal convention in VW-speak that front means front of car, not "closest to what I'm looking at". So the fan belt is at the rear of the engine and the clutch is at the front.

If you are new to VWs, remember that all bolts/screws are metric, so it's a good idea to get a set of metric box wrenches (ring spanners in Aussie-speak :-), open-end wrenches and socket wrenches. The main sizes you will use are 6mm, 8mm, 10mm, 13mm, 14mm and 17mm (17mm needed if you ever decide to remove the engine from the car :-)

Before you remove the muffler, have a real close look at the fittings where the exhaust pipes for the front cylinders (front is front of car remember) curve back through the heat exchangers to meet the muffler -- that's the lower exhaust fittings on the front of the muffler itself. The upper pipes bolt directly to the head (with two studs each side, they can often be rusty and hard to get moving) but the lower fittings are a sleeve fitting with a clamp around them. The ends of the exhaust pipe itself go into the muffler sleeve, and these stub ends eventually rust away, causing exhaust leaks and can eventually break off entirely. You can get replacement stub ends if needed - you saw off any remaining rusty end back to the collar which is right next to the heat exchanger (which surrounds those exhaust pipes), and then hammer the new end into the exhaust pipe before fitting a new muffler.

The ultimate repair for these is to replace the complete heat exchanger, but the replacement stubs will do a good job if the rest of the heat exchanger is in good condition.

I mention this as you said the underside has not had attention for a long time and everything looks a bit rusty, so it's worth checking this out before you start the removal so if you need the replacement stubs you have them handy.

The visual check is to look at the pipe between the clamp on the front of the muffler, and the heat exchanger itself - only about 1 inch of exhaust pipe is exposed, but you'll be able to tell if the stub-end looks badly eaten away, and may see black sooty marks where exhaust gases are shooting forwards out of the sleeve muffler fitting, if it's badly worn. Any exhaust leaks here can often be smelt with the heaters on inside the car - that exhaust gas squirts straight at the heat exchangers and they are only stamped metal sheeting surrounding the exhaust pipe, so are "leaky".

Hopefully the muffler kit will have all the normal fittings needed -- clamps, fat fibre washers for the lower sleeve fittings, flange gaskets for the upper fittings and so on. When buying a muffler, it pays to check if it's a "complete muffler kit" first - not just the bare muffler.

One tip for inserting the peashooter exhaust tips into the installed muffler... tap them in as far as they can go and then pull them back out about an inch (exact distance is not critical). The reason is that inside the muffler is a couple of cross-over pipes for the rear cylinder connections (so each cylinder has a header pipe of the same length but the front two cylinders have there header pipe exposed and surrounded by the heat exchangers). If you tap the exhaust tips hard up against the internal header pipes, you'll create a slight back pressure inside the muffler (partly block the exhaust tips). Once the muffler is installed, the exhaust tips should project an inch or so past the bumper bar.

One further point (they keep coming don't they!) - your muffler kit should come with small flange gaskets for the two ends of this heat riser. Originally VW had a smaller hole in one gasket and a larger hole in the other, to control the amount of gas flow in the heat riser. If your kit has the same sized holes it's no problem (just runs the heat riser a little hotter), but if it has the small/large hole arrangement, the small hole goes on the DOWN side of the heat riser - that's the side with the curved pipe into the front of the muffler. I can't tell you which side that will be - I've seem replacement mufflers are made which work in either direction - the curved pipe can be on either side.

Some muffler kits don't even have the curved pipe these days, they have an extended fitting on both upper flange fittings (for the rear cylinders) which means gases pulse back and forth between the two rear cylinder muffler flanges. In this case, the large-hole flange gaskets are definitely needed as the gas flow is less with the pulsing fitting. Also make sure that the holes in these flanges on the new muffler are drilled right through into the exhaust pipe - some replacement mufflers have the fitting but leave it undrilled so the gases cant flow and the heat riser is therefore inoperative. They still HAVE to have the fitting itself since the heat riser supports the weight of the carby - stops the centre section of the main inlet manifold rotating in the rubber boots which it would do with the weight of the carburetor slightly rearward of the inlet manifold as it is.

As you can see - everthing on the VW engine is inter-related and relies on "something else" to be there too - but they are easy engines to work on compared to most modern engines, and they sure reward you with a nice ride when they have had a dose of TLC :-)

Whew - that ended up longer than I though it would, but if you are new to VW repairs, you might find it useful stuff to know.

The standard beetle muffler is surprisingly efficient for the cramped space. They cope with this by having the two front cylinders exhaust straight into the muffler (via the heat exchangers which are also the headers), but the two rear cylinders have headers internally in the muffler. The header pipes actually cross over inside, so the left rear vents close to the right tail pipe and vice versa. (This is part of the reason for the distinctive beat of the VW engine.) This gives each cylinder an equal length header, but no extractor effect, as the gasses just mix any-old-how inside the muffler before exiting the tail pipes. A well-designed extractor can therefore get about 2-3 hp extra, without any other alterations to the engine. Trouble is, most extractors either have a low hanging muffler (the extra pipes take up the original muffler space), or the muffler has to hide under a rear fender, behind the wheel.

I’m not sure what you mean by the “extractor system.” Please enlighten me.

The term “extractor” here means equal-length header pipes then running 4 into 1 before the muffler. The angle of the 4-into-1 fitting is as shallow as possible so the exhaust gas from one cylinder rushing past the other three “openings” at the join causes a reduction in pressure in those three pipes, so when the next exhaust valve opens, the gases are partially “extracted” by the lower pressure. The length of the header pipe before the join is important to “tune” the pipes to the engine speeds, too short or too long and you get unwanted harmonics in the exhaust stream which interferes with the “extracting” process. Even on drag racers without the 4 into 1 (or 8 into 1 etc), you still see the header pipes, and the length of these is important -- short pipes for high revs. I read somewhere that the VW engine needs at least 20 inches on each header before they join up.

Out muffler is the Sports GT style... It would be fine except that the exhaust pipe that runs from the heater box outlet into the muffler goes directly underneath the hole in the engine tin that the fresh air tube is to pass through...

Trouble with the rear headers is that you still have to get access to the two exhaust mounting bolts, so they can’t easily turn the pipes too sharply to get it out of the way of the heater hoses. This is why on the original system the exhaust header runs THROUGH the (fattened) heater pipes.

"Equal length" ... "4 into 1". I do count four pipes running into the muffler, two from the #1 and #3 cylinders that pass through the heater boxes, and two from the #2 and #4 cylinders in the rear. But these don't seem to be equal length, and do they combine "4 into 1" inside the muffler box?

The standard muffler does have four equal-length pipes, but two of them hide inside the muffler itself (the rear cylinders). And in the standard muffler, each header pipe has it's own separate open end inside the muffler -- there is no smooth 4-into-1 plumbing.

Looking from the rear of the car:

The === represents the rear cylinder headers crossing over inside the muffler. The // bit is supposed to show #2 internal header bypassing the internal header for #4. Both pipes are in fact almost straight-- across the inside of the muffler, and almost touch each other. The outlet for each is near the 'opposite' tailpipe. #3 and #4 have very short conical ends with holes in them, pointing straight at the rear of the muffler (end on in the diagram above, so simply shown as 'O's).

The centre 'O's represent the peashooter tail pipes.

The four other 'o's represent the inlets on the front side for each cylinder. The bottom ones come via the heat exchangers, which are the headers for the front cylinders.

The 4-into-1 systems have exposed pipes curling around where the normal muffler sits, with the 4-into-1 join in the centre, and usually have an in line muffler (one pipe in, one pipe out) under the rear apron/bumper much less ground clearance. The alternative is to take that one outlet pipe (4 into 1) over to the area behind one fender/rear wheel, and place the muffler there.

The stuffing in the peashooters is the actual muffler -- the 'muffler' is just an open expansion box. Take the peashooters off and it's quite loud.

A variation to this is the 4-into-2-into-1, with cylinders 4 and 1 joined, and 2 and 3 joined (it has to be this combination to get the right harmonics in the exhaust pulses), then these two outlets combined after about a foot, then the 'in line' muffler after that.

Our car had the non-standard GT Sports Style exhaust system when we bought it. It has chromed bell tips rather than "peashooters" ("contain resonators that combine to produce a smooth, mellow exhaust note" -- direct quote from the Rocky Mountain Motorworks catalog). Sounds a little noisy to me, but my son really likes the way it looks ("Cool!"). The muffler has an exit point on either side of the expansion chamber (thus two), each of which divides in two to end in two kewl chrome-plated tail pipes (four altogether). The car definitely "fweems" -- it's a little on the loud side but kinda mellow, much like a glass pack. This muffler is not a particularly good fit around the heater holes in the tinware.

The exhaust pipe that runs from the heater box outlet into the muffler goes almost directly underneath the hole in the engine tin that the fresh air tube is to pass through. A serious interference that could have been easily corrected in the design. My "thinking it out again" hasn't come up with a good fix as yet. I think this is the main reason why hot air flow up the left side is restricted (and of course the left side is the more important one here in the States, being the driver's side and thus the side that needs a clear windshield the most).

I guess with the GT system you don't have the normal metal tube bit under the tinware to the heat exchangers, and have to extend the 'paper' tubes through the tinware to the heat exchanger itself? I seem to remember you describing this in one of our earliest emails. Makes for less potential leaks, but as you say, it can be an awkward fit around the exhaust pipes. Also a potential for chaffing where it goes through the tinware.

The muffler I have on mine at present isn’t a good fit around the heater holes in the tinware either, and I had to construct a special fitting each side to poke up through the tinware, mating to the metal tube which surrounds the rear cylinder exhaust pipes. They look like two very short tubes soldered one on top of the other, but slightly offset, and with a slight kink as well. Made them up from a bake beans tin and solder. It's worked very well, but it SHOULDN'T be necessary.

It's a Brazilian made muffler I bet. I'll choose the next one very carefully -- and not too long to go either I think -- it's looking on it's last legs now.

If I had the equipment, I'd love to try building an extractor exhaust system myself, and see if I could fit it AND a muffler (small 'hot-dog' type) in the same space without hanging under the car. A real contortionist exercise -- both mental and physical. The physics are not too difficult, you just need each header pipe the same length, and at least 20 inches long before they join, and get the 4-into-1 join at 45 degrees or less for best 'extraction'. I don't have a pipe bender or mig welder, so I guess it will remain a 'pipe' dream. :-)

How new is your muffler? If it's getting close to replacement, you can choose a muffler with the heater bits, or with room to mount them.

I’ll look into this -- I'm sure the muffler will need to be replaced in the not-too-distant future. Remember, though -- I walk a fine line between functionality and "cool"! My son really likes the look of this sports style muffler and its four chrome bell tips!

I discovered the other night that we're probably going to have to replace the muffler soon. I noticed that one of the two sets of bell tips was out of kilter (pointing a little inward) -- I must have grabbed it when skooching myself out from under the car. Obviously the metal is weakened and will probably fail soon. I find the muffler for $75 at RMMW and for $45 at Unique Supply, Inc. A difference in price like that makes me wonder. I like to get things as cheaply as possible, but I'm also convinced that you get what you pay for. I've developed a bit of confidence in RMMW, but is that worth 30 bucks?

The one thing I see on RAMVA all the time is "buy good quality". So I'd be asking questions about the cheap one (Mex/German/Korean or what?).

Exactly my thinking. I guess I have more confidence in the stuff from RMMW than in the folks who advertise in the VW mags. Will be asking lots of questions before deciding.

Tonight I made an unpleasant discovery (that I suspected I'd soon find). I found a crack where the tail pipe attaches to the muffler on the right side -- I thought the car sounded awfully noisy. So off to the auto parts store and got some "Muffler Mender" -- I'm not in the mood to replace the muffler right now!

I stretched out in back of the car and filled the crack between the muffler and the right tail pipe with JB Weld, then pulled it back into place and held it with string to set up. We'll see what it looks like tomorrow morning. May need to use some of that Muffler Mender stuff, too. Will probably need to replace the muffler before September, but don't want to do it now. (Not as worried about it as I was, given the promises that the much-touted Kroil penetrating oil makes.)

Even on the standard muffler (which I'll soon be replacing) I'm not looking forward to removing it -- can only get 1/12 turn at a time on one of the nuts as I recall (been about 5 years since I last replaced a muffler).

Get yourself some Kroil (or equivalent) penetrating oil -- wonderful stuff.

I replaced the muffler (another GT Sports model) with no problems (other than the same alignment problem with the preheater tube connections).

I expected that getting the muffler bolts (nuts) off would be a rotten job. Actually, with liberal use of Kroil, it turned out to be piece of cake. What was frustrating was that the muffler was still very tightly bound up between the engine and the rear apron, even with all the nuts off. To get it out we had to remove the right heater box.

I presume you mean the non-standard muffler uses more space than the original, or is it because you already had the engine part way back?

Having the engine back was part of it. But this GT Sports style muffler sits at an angle immediately in front of the rear apron -- I don't think it would be possible to get the engine out with this muffler attached.

While laying on my back looking up at the wedged-in muffler I noticed from the inside the two little cutouts (I don't know what to call them) that the peashooters on the stock muffler extended through towards the rear. Whoever "customized" this car installed a new rear apron right over the top of these cutouts so that the bottom of the apron is level all the way across. The four large chrome bells on the GT Sports muffler (two on each side) extend out the back below the lower edge of the rear apron.

A question -- do you know what the two little box-shaped protuberances on the outside front (near the #2 and #4 spark plugs) are in aide of? I can't see any useful purpose for them. And it appears that these pieces are supposed to bolt to the fan housing -- there is a captured nut on the other side of the hole for the purpose. In general, do you know the utility of these pieces? I'm hoping they will help keep exhaust gases out of the engine compartment.

Hopefully there will be no exhaust gases to keep out (once the heat risers are bolted up right :-) but these pieces ensure that there is no mixing of used cooling air with the upper side of the engine. There is a partial vacuum in the upper engine compartment when the fan is running and higher pressure air right at that point as the cooling air exits the head area, so any dirty/used air underneath will be attracted upwards through those holes to contaminate the fresh cooling air.

And yes -- they do bolt up to the fan shroud. On mine they have some lagging on the underside, which is supposed to seal around the heat riser pipe. Even if this is missing on yours, it will sure help a lot to have them there.

But they seem to be designed with some other purpose in mind. Most people just take them off and throw them away, I'm told.

And most times you'd get away with it I think (so long as there are no exhaust leaks to get into the fan and heaters :-), but in hot climates the mixing of used cooling air with the fresh stuff might cause some engine overheating.

One interesting thing I DID notice though -- looking at that exhaust port, it looks very much like you've been getting some exhaust leaking out both sides of the join -- the area around the studs is clean but in between is very black. Might this be the source of smelly cabin heaters? Might need two gaskets so you can get a bit more "squash" to seal the area better.

I can’t fix the cabin heater until I either work the paper tube past the header exhaust system to connect to the heat exchangers, or replace the muffler so the correct fittings are in place.

I'd opt for the latter, if you can afford it.

That's what I want to do, but first I have to find a working heat-riser section of the manifold. Two places said they'd sell me one, but it would certainly be clogged completely. I'd like to avoid hours of work clearing one if I can.

It's more pricey if I go "standard muffler" but this (plus a replacement heat riser manifold section) will also give me carby de-icing, which I will need occasionally in winter. A present I have neither cabin heat nor heat riser connections available with this weird exhaust.

The standard muffler sounds like the best.

One small oddity. The current replacement mufflers have the heat moving the opposite way through the heat riser -- the small diameter curly pipe is on the right side of the muffler, not the left.

On the original system, it takes the exhaust gas from the right rear (#2) via the fitting there, flows right to left, and the left fitting is the curved pipe to the "front" on the muffler opposite the left peashooter. On this muffler, the flow is left to right, and the curved pipe curls down behind the right peashooter. Since this is the side used for the carby inlet pre-heater, the space is mighty tight, and the elbow (the metal pipe under the tinware which pulls air from the cylinder head area) for the pre-heater "sits" on the curved pipe - the curved pipe really needs a dip in it to clear the pre-heater elbow properly.

The right side cabin heater bugly bit which takes the air from the paper tube around the #2 header and into the heat exchanger doesn't quite line up with the hole in the rear tinware either. I've had to make an offset tube out of a cat-food tin so I can get cabin heat on the right side. It looks like a tube cut into two shooter tubes, and then placed back together but slightly offset so there are "new moon" shaped gaps on both sides. These I've filled with soldered bits of cut cat-food tin. The tubes themselves are soldered too. It works well, although the slight restriction in the inside of the tube becuase of the offset probably reduces the flow a little.

I had to do this with a muffler I got for my 1970 Bug many years ago too -- I thought it was probably an aberration, but it seems that's not the case. You'd think it would be easy enough to alter the pattern a little so they line up better. The only other alternative would have been to cut a larger hole in the tinware, and then you'd have more air leakage from under to upper areas of the engine bay, and with the solid engine lid I on my newer Bug I DON'T need any cooling air leakage.

A picture in the Rocky Mountain Motorworks catalog shows the small diameter "curly pipe" on the right side of the muffler and the right side of the "bulgy thing" after 1963. The "curly pipe" moved from the right to the left side of the right-hand "bulgy thing" between 1965 and 1966.

The curly pipe was on the left side of the muffler when I bought my ’70 Bug (exhaust flow right to left). Seems that they've settled on left to right flow (curly pipe on the right) for all the South African made mufflers we get here in Australia. With the Australian dollar being low compared to the US and European countries, getting mufflers from these sources is prohibitive. The German made complete kits (with peashooters, clamps etc) is over $200 Australian!

A single peashooter here (South African made) is around $10 - I think it was about $3.45 US in the RMMW catalogue.

I want more power, but want to stay mostly stock. I hate extractor headers, and have had some over the years, and concluded the performance advantage really isn’t worth the ground clearance etc., heat, etc.

That's true (ground clearance), although there are several extractor types which use a muffler tucked up behind the right rear wheel, and the only "lower" part of the system is the connecting pipe from the extractor to the muffler, and this just dips down under the right rear wheel arch area - no biggy.

However, I must agree with you that the standard muffler is hard to beat for convenience, and it's surprisingly efficient too.

If you do stay with the standard set-up, one thing I'd check is that when you buy a new muffler, have a look inside it where the lower cylinder headers slide in. Most standard mufflers have a cone shape in there with small holes through it, so the exhaust gases get dispersed as they enter the muffler. On the one I just fitted, this cone had only a few of it's holes properly exposed inside the muffler, the rest were blocked by the sides of the hole the cone sits in. I drilled out some of the good holes a little larger, just so there was no restriction to the exhaust.

So, here I'm again mixed up with a couple of new doubts. It started when my muffler failed. I've got the car to the repair shop the mechanic and I noticed that one stud has been broken in the past, so, I need to pull the engine down to re-thread the hole.

Yes -- that needs to be fixed. While you have the muffler off, check that the heat riser is still clear -- it can be done with the manifold still on the car, and there is a procedure for it on our Web site . The heat riser starts to get blocked with carbon as the engine slowly wears out and starts to burn a little oil.

I've been calling around today trying to find something to insulate the rear apron with. Finally it was suggested to me that instead of trying to put something on the inside of the apron, I should insulate the muffler itself. I understand that something called "header wrap" is made precisely for that purpose.

NAPA will sell me a 10-ft piece (every place else I called would only sell it in 50-ft rolls), so I'm going to go down there tonight and pick some up. I guess it will have to be wired to the muffler.

Sounds like it would work. The only problem I can see is that short runs would produce condensation under the wrap (repeated heating a cooling would draw air into the gaps in the wrap), which might cause the muffler to rust out sooner. I've seen comments about this on the newsgroup a couple of times.

I wouldn't be a big problem if the car is normally driven more than about 5 miles a time I would think -- that should be enough to cook out any moisture from the previous cooling.

Just recently I replaced the tailpipes on my ‘71 Super. Prior to that, the vehicle had the classic 'vreem' sound to it. Now it doesn't. What happened? The pipes look and seem identical to the old ones and were bought from Aircooled.Net on the web. I seated them in as far as they would go in the muffler. Should they not be in that far? Or does that matter? That's the only thing I did. Muffler is the same.

Inside the muffler are two "header" pipes which cross over each other, so that all cylinders have a header pipe the same length - the front cylinders have the heat exchanger pipes, and the rear cylinders have their pipes hidden inside the muffler.

When you push the peashooter exhaust pipes all the way in - they hit those header pipes, and may partially block the entrance to the peashooter - this can alter the sound.

Try pulling the peashooters out about an inch, and see if this makes a difference.

I suppose the peashooters DO have the internal perforated pipe and stuffing between the perforated pipe and the chrome outer pipe?

THIS is what provides most of the casual muffling - the "muffler" is in fact an open expansion chamber, which provides little muffling in itself.

The only thing that scares is me that I'm going to remove the old muffler, go to bolt the new one on and have one of the parts/hoses that it connects to fall apart in my hands (EVERYTHING under there looks pretty rusted as you can imagine.

Before I start...you may already know this but because the VW is rear engined, front and rear descriptions can easily get mixed up -- it's normal convention in VW-speak that front means front of car, not "closest to what I'm looking at". So the fan belt is at the rear of the engine and the clutch is at the front.

If you are new to VWs, remember that all bolts/screws are metric, so it's a good idea to get a set of metric box wrenches (ring spanners in Aussie-speak :-), open-end wrenches and socket wrenches. The main sizes you will use are 6mm, 8mm, 10mm, 13mm, 14mm and 17mm (17mm needed if you ever decide to remove the engine from the car. :-)

Before you remove the muffler, have a real close look at the fittings where the exhaust pipes for the front cylinders (front is front of car remember) curve back through the heat exchangers to meet the muffler - that's the lower exhaust fittings on the front of the muffler itself. The upper pipes bolt directly to the head (with two studs each side, and they can often be rusty and hard to get moving) but the lower fittings are a sleeve fitting with a clamp around them. The ends of the exhaust pipe itself go into the muffler sleeve, and these stub ends eventually rust away, causing exhaust leaks and can eventually break off entirely. You can get replacement stub ends if needed - you saw off any remaining rusty end back to the collar which is right next to the heat exchanger (which surrounds those exhaust pipes), and then hammer the new end into the exhaust pipe before fitting a new muffler.

The ultimate repair for these is to replace the complete heat exchanger, but the replacement stubs will do a good job if the rest of the heat exchanger is in good condition.

I mention this as you said the underside has not had attention for a long time and everything looks a bit rusty, so it's worth checking this out before you start the removal so if you need the replacement stubs you have them handy.

The visual check is to look at the pipe between the clamp on the front of the muffler, and the heat exchanger itself - only about 1 inch of exhaust pipe is exposed, but you'll be able to tell if the stub-end looks badly eaten away, and may see black sooty marks where exhaust gases are shooting forwards out of the sleeve muffler fitting, if it's badly worn. Any exhaust leaks here can often be smelt with the heaters on inside the car - that exhaust gas squirts straight at the heat exchangers and they are only stamped metal sheeting surrounding the exhuast pipe, so are "leaky".

Hopefully the muffler kit will have all the normal fittings needed - clamps, fat fibre washers for the lower sleeve fittings, flange gaskets for the upper fittings and so on. When buying a muffler, it pays to check if it's a "complete muffler kit" first - not just the bare muffler.

One tip for inserting the peashooter exhaust tips into the installed muffler... tap them in as far as they can go and then pull them back out about an inch (exact distance is not critical). The reason is that inside the muffler is a couple of cross-over pipes for the rear cylinder connections (so each cylinder has a header pipe of the same length but the front two cylinders have there header pipe exposed and surrounded by the heat exchangers). If you tap the exhaust tips hard up against the internal header pipes, you'll create a slight back pressure inside the muffler (partly block the exhaust tips). Once the muffler is installed, the exhaust tips should project an inch or so past the bumper bar.

Oh - and one further check before you start -- does your heat riser get nice and hot when the car is running?

The heat riser is the smaller horizontal pipe under the main horizontal inlet manifold -- it has exhaust gases running through it to warm up the inlet manifold and prevent icing under the carb - it's VERY important to have this working or the engine will suffer icing and stumbling on cooler days. When the engine has been warmed up, this heat riser should be sizzling hot at the ends near the heads (finger burning hot), and the main inlet pipe above should be warm to touch. If it's working well, it may be hotter at one end and just very warm at the other - depending on the muffler design (see below). This is normal - the original muffler design has a one-way flow of exhaust gases through the heat riser, so the "up" side will be a little hotter.

If the heat riser is only luke warm or even cold, it's been blocked by crud in the exhaust gases and needs to be reamed out whilst you have the muffler off.

There's a procedure for Clearing a Blocked Heat Riser on our main Web site. You won't be able to do the "final" ream described there -- upending and soaking it overnight with carb cleaner, but just a ream-out as described (if needed) will get good results.

One further point (they keep coming don't they!) - your muffler kit should come with small flange gaskets for the two ends of this heat riser. Originally VW had a smaller hole in one gasket and a larger hole in the other, to control the amount of gas flow in the heat riser. If your kit has the same sized holes it's no problem (just runs the heat riser a little hotter), but if it has the small/large hole arrangement, the small hole goes on the DOWN side of the heat riser - that's the side with the curved pipe into the front of the muffler. I can't tell you which side that will be - I've seem replacement mufflers are made which work in either direction - the curved pipe can be on either side.

Some muffler kits don't even have the curved pipe these days, they have an extended fitting on both upper flange fittings (for the rear cylinders) which means gases pulse back and forth between the two rear cylinder muffler flanges. In this case, the large-hole flange gaskets are definitely needed as the gas flow is less with the pulsing fitting. Also make sure that the holes in these flanges on the new muffler are drilled right through into the exhaust pipe - some replacement mufflers have the fitting but leave it undrilled so the gases cant flow and the heat riser is therefore inoperative. They still HAVE to have the fitting itself since the heat riser supports the weight of the carby - stops the centre section of the main inlet manifold rotating in the rubber boots which it would do with the weight of the carburetor slightly rearward of the inlet manifold as it is.

As you can see - everything on the VW engine is inter-related and relies on "something else" to be there too - but they are easy engines to work on compared to most modern engines, and they sure reward you with a nice ride when they have had a dose of TLC :-)

Whew - that ended up longer than I though it would, but if you are new to VW repairs, you might find it useful stuff to know.

It's the design that makes it a bit more noisy -- "Sports GT."

Yes -- I remembered it was a sports muffler, but you hadn't commented before on it being particularly noisy compared to the standard one.

We always know when our son is coming home -- several blocks before he arrives!

Oh - the LOUD kind of mellow :-)

It sure looks "cool," though, with those four chrome tips! It's because of the muffler that I installed the fiberglass rear apron without the cutouts for the pea-shooters. So we're committed! :-)