Well the combo will be TW heads that have had all the casting flash removed (polished runners and combustion chambers), an Edelbrock RPM EFI intake (also with polished runners in the lower), more than likely a FTI cam, on a stock shortblock 302 in my 88' notch that weighs pretty close to 3200 with me in it. Now I know that the 1 5/8" would probably be best for now, but how much would 1 3/4" hurt this setup? As I'll probably up the ante with a stroker or a blower sometime in the future (who knows how long though). So what I'm really asking is when do you need to step up to a 1 3/4"???