The new dual ball bearing PT70 GT-Q turbo (7080RH) will support up to 850 fwhp and the non bb version has proven to take many TSM legal cars into the mid 9s. With this turbo and a 9" or 9.5" converter that can flash stall to around 3800, you should be able to bracket race this combo very easily. If you want low 9's and you have a 248 ci motor, I would run the same converter, but go with a PT74 GT-Q with the dual ball bearing cartridge.(7480RH) This turbo will support up to 950 fwhp. A 3500# Buick will need to put down approximately 900whp to run 9 teens at 148. To make this kind of power with a 74mm turbo, you will also need to run a converter that has very low slippage, aka low drive train loss. I prefer the 74mm wheel to the 76 because the 74mm wheel makes more power through out the entire rpm band than the 76 does. The 76 wheel is more peaky and only makes more at higher rpms. I don't particularly care for the 72mm wheel, the 74 will way out perform it with little to no difference in spool up. Also, with regards to your combo, I hope you have a good external pump such as a Weldon DB2015a or a DB2025a. Anything less just ain't gonna cut it at this power level.
Just my O2's worth.
Patrick
