I was just wondering if anyone has actually gone to a bigger throttle body from maxing out there stock one. I was reading in the pcm section that a guy was pulling vacuum at WOT and kind of wondered this... Oh ya and im also pulling 2 hg of vac at WOT myself, im not quite sure why but im thinking it might be the TB for myself i just haven't heard of anyone maxing out there TB but wasn't sure

 

Interesting findings on your Hg readings. I am not sure if there is an apples to apples comparison bewteen your LT1 style motor vs the LSx based ones. Most of the TB mods on the LSx do not have much impact unless running bigger cubes like you are. The LSx ones are already over 70mm ( single bore ) stock.
You might also post in the car sections as they tend to play with the TB sizing more than us truck folks...