Originally posted by Dan Nixon:
... On the good side, a 2-4 HP gain from removal of only the plate suggests that optimizing the butterflies (similar to the t.body) may give some gains without the issues of removal.
Optimizing the lower IM does help out and it can be done for the cost of a couple of gaskets and some screws. After a good cleaning, the screw heads and extra threads can be smoothed out to provide better/more air flow. I felt the TB had a bigger impact, but the lower IM butterflies is also worthwhile.
