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

How much did you have to remove? (Roughly)
Pics?

@RustyRatRod
Rob, what did you measure, ~1 7/8 stock at the flange?

I did a couple of these, I gasket matched mine, bolted a flange gasket to the manifold flange and marked the inside of the gasket on manifold itself and the 1st thing I noticed on both that I did, was how far off center the hole in the manifold was compared to the hole in the gasket.
I wound up grinding about 3/4 of the way around the outlet in the manifold, about 1/4" at the thickest point to almost none in the thin spot, (thin, as in part of original outlet hole that is closest to flange gasket already as cast, with little grinding needed to match the location of the gasket as bolted to the mounting holes) the casting was still quite beefy all around once I was done. I think I could get 2-1/2" and still have plenty of meat left in the casting.
The 2nd manifold I did was still off center to the flange gasket ,but not as bad// had to take material out all the way around, but still not the same amount all the way around to match the gasket location. I blended both all the way back into the manifold as far as I could reach.

the first one was 1 13/16 with all the snot. i gasket matched it, sprayed and grinded,