ok, first of all, for the late model bonnevilles, ZZP sells a LS1 conversion kit to take it up to 75.5mm. but you need to use the mini afc maf calibrator they sell to use it. i have a 92 ssei. i have a 95 SC on it. the opening on the sc is 74mm. i tried a 95 Tb before and it ran like crap. too much unmetered air . so i went back to my stock TB. well , after talking to a fellow racer at the track with a 13.44 sec 98 regal GS, he showed me the LS1 conversion and it had the mini afc on it .so i got another 95 TB , (92-93 TB is 58mm, 94-95 TB is 70mm) and recalibrated my MAF with the mini afc to show 128%, and WOOOOOOWWWWWWW. what a difference., the only hold back on doing this to a 92-93 is that the inlet for the SC is only like 58-60mm, so unless you go to a 94-95 sc, there will be very little or no gain in going to a larger TB because the Sc inlet will restrict it.