PROBE GT GLOSSARY -- Back U Underdrive Pulley Currently othe only manufacturer of underdrive pulleys for the 2.5L-V6 is Unorthodox Racing (www.unorthodoxracing.com). The power benefit from the pulley is not dramatic. Dyno runs have  measured 3-5hp gains. It has been claimed that there can be problems with the sawtooth timing ring on the pulley -- it is not always aligned correctly resulting in incorrect ignition timing. V VRIS (Variable Resonance Induction System) One of the unique parts of Mazda's KL V6's. The intake manifold is made from cast aluminum and  contains electronically controlled butterfly valves. Depending on throttle position, and engine RPM, the valves alter the effective intake passage length and thereby change the intake resonance  frequency, hence the name Variable Resonance Induction System. For more on the VRIS, click here... VRIS Heaven (warning: lots of graphics). Here's a shot of the VRIS casting interior with the 'U' resonance tube removed. Notice the lip that  was not machined off completely. It might be a good idea to grind it off. It lies directly in the direction of airflow at 0-4250 and 6500-7500RPM when VRIS valve#2 is closed. W Wheels If you want to avoid the expense of buying new wheels, or simply want to preserve the stock tire appearance, stick a set of 245-45-16 tires on the stock rims. I you still want aftermarket wheels,  here are three of the best looking wheels I've seen so far for our Probes... My definite favourite wheel, Enkei Shoguns. Similar to '95-'97 stock wheels. Reportedly available through U.S. Sears(!!!) by special order. 17" Borbet Type C's with 235-45-17s. Sorry, I don't remember who's picture this was. Michel Fortier's ( http://members.aol.com/suprprobe/Welcome.html ) 245/45-17 tires. Axis Touring Cup Wheels with 235-40-17's. Wild Orchid Very cool colour. Introduced in the 1994 model year. X   Y   Z       Counter installed April 1, 1999