So all in all, it really wasn't worth the hassle, especially since you can buy something better?
I did it a while ago before the FAST. At the time only the BBK which was 80mm was available. I can tell you I made 347rwhp/352/rwtq with just an LS6 manifold the TB and Stainless Works headers with X-Pipe and Corsa's. Before I did the bolt-on's and with just an x-pipe and corsa's with VaraRam I did 316rwhp.
I would say I picked up a few hp/tq, but yes with what's available now, I would put it in the drawer and spend the money for a larger TB. That is if you're ready to do a tune.
It was a cool project for a boring weekend at the time though.
If you do decide to do it, be careful of the lip right at the bottom of the blade in the body. Be careful to not mess with it's contour, or it will screw up your idle transition. I touched mine only a bit and it was affected, but not much, so it's a sensative area.