Now I know the difference between TPI and TBI but whats the basic difference between MPFI (Multiport Fuel Injection) and TPI? From what I can tell they seem the same. 1 injector per cylinder, air intake ducting looks similar. Is the difference between the engines they decided to put it on (MPFI - 2.8L, TPI - V8's) or is there a big difference functionally?

TPI is MPFI, but with tuned runners to provide peak torque in the engines midrange.

and wow you can really feel it!

Alright I guess that helps, I was kinda curious as to why they didn't have the same name.
----------
Yeah amazing what those runners can do (oh and that extra 177 ci too, pfft)

MPFI is the general name for any EFI system with one (or more) injector per cylinder. TPI is the specific name for the MPFI engine in V8 thirdgen f-bodies and 85-91 Corvettes.