If this is going on a Buick V6, then I personally would recommend a PT74 GT-Q dual ball bearing with either a .68 A/R T4 tangential or a .81 A/R T4 tangential v-band style PTE turbine housing. (A/R would be determined by CI of the motor) If the CI is 248 or smaller, then the .68 would work just fine as it will definitely out flow the 3-bolt .85 PTE housing. If the motor is larger than 248CI, I'd say go with the .81 A/R. But in order to maintain decent spool up manners, you will need the dual ball bearing cartridge no matter what. The 74mm compressor wheel has a much more usable power curve than the 76mm compressor wheel does, and you have an advantage with having a 3200# car with driver. This turbo will easily support 850 flywheel hp when maxed out, and if you car weighs 3200#s with driver, you only need to make in the neighborhood of 760-780 flywheel hp to go 145mph in the 1/4, which should be enough for easy mid 9s. The 76mm compressor wheel will make slightly more hp at higher rpms than the 74 will, (about 15 more) but the 74 will make more power in the low to mid range of your power curve. Either one will get the job done, but if you intend to play with the car some on the street, the 74 will feel more peppy. You do not need the GT-S turbine wheel on such a small V6. (231-248 CI) The GT-Q will get the job done just fine.
Hope some of this helps a little.
Patrick
