the 5.7 likes the 80mm over the 85mm. I would go 85 if you have major mods internally, or running boost. 80mm for a mostly stock motor with bolt ons and tune
I had forgotten a tapered boreNot the case if you go with a taper ported 85mm, as you get the best of both worlds. Unlike a straight bore 85, no tuning is needed for A/F, and I immediatley noticed better throttle response at all RPM. The modern Muscle 85 TB was the second mod I put on after catch can.
Catch Can is the first thing to get. Not only keeps the throttle body and intake from getting caked, the Hemi runs better. WIth the stock setup, when those unburnt hydrocarbons are fed back in to the intake through the PCV, the effective octane number is reduced, and the ECU pulls timing.