The GM stuff seems to be the standard of the aftermarket EFI industry. Almost every system I have seen uses GM sensors (some dont admit it but they sure look identical down to the partnumbers). The thing about the TBIs I think that there are just shear numbers of them out there in the junk yards and on the rebuild shelfs in stores since every GM truck built had essentially the same part on it from 87-95. Those are prime years for the 'u pull' cheap junkyards now. From what I gather if the throttle body is too big it just takes some tweaking of the tuning to the the smooth drivability. My setup (TBI) is hard to drive on wet roads because there is too much throttle response, it even chirps the tires on a dry day (not bad for a 6000lb FWD car). When I get around to hooking the timing control up (still running mech/vac now) I hope to be able to mellow out that initial slow tip in by retarding the timing a bit in that area without changing or hurting the performance everywhere else.
