4AGE is not in the same league as a 4g63t, SR20,F20C (or even a B16). The Cosworth YBT, Duratec 4 and 411BT should all be listed here as well. The Duratec's are pretty badass (not many aluminum blocks out their that can handle 50psi of boost). The YBT is legendary (yes I know i misspelled it YBB in my earlier post but whatever it was late).