porting exhaust manifold

i hogged out my dartlite manifold to 2 1/4, with the ny hills i noticed alot less down shifting
still compiling the data if there's mpg gained. doing the 1 on my van right now. i had a 2 1/4 ehaust put on with the muffler slant6 dan recommended. feels better. so far. need maifold put on. i'll give results.
it would be cool if we had a dyno result test, with stock, hogged out 2 1/4, header, n dutra duel results