The hypertech chip & thermostat setup is a popular yet pricey mod.  You've probably heard mixed stories about how chips tune your engine.  Some good and some bad.  Well here's the truth about chips from my experience.....

You want to tune your 2.8/3.1L with a chip?.. Expect good gas mileage and thats it.   The fact remains that if you want your chip to give you even a minor 6-9 HP boost, you're going to have to spend alot more time or money  making that chip work for you (I'll explain this later).  What that chip does is increase the timing of your engine.  It also turns the radiator fan(s) on earlier to keep your engine nice and cool.  It does a lot of other neat things that only apply if certain conditions are met.  Now to further explain this point:  You're going to have to perform more modifications on your car to make that chip work for the money you bought it for.  Upgrading the Exhaust system, Intake and Cylinder Block, are great examples of what you need to do to make that chip give you that 6-9 extra HP... Essentially you have to make the engine more efficient to be more efficient ! So that means more time and money spent.  If you have a bone stock engine, the only difference you'll see is an increase in gas mileage and 1-2 extra HP.  Doesn't seem to be that worth it now does it?... My recommendation: do your engine up.. then get the chip to get a 10HP boost.