I read somewhere that the older generation of 4EFE's, (the one found in the EP80) came with a 4-2-1 manifold instead of the 4-1 that we get on the EP91's. What sort of difference would you get, I know with different manifolds you get more power at difference rev ranges, but I can't remember any of it, someone wanna shed some light? Basically what I want to know is which one would be better for low end/mid range/top end. And if they're both a straight swap. thanks in advance