The tranny held at the 570 range although I'm sure the drag racing took a toll before it went. My very first hard run with Flux 2's, F1 springs, TNT-R and O-rings grenaded 4th gear like it was nothing. The boost went to 60psi and BOOM!!!!!

I would have complete faith in drag racing a G56 in the very low 500 or upper 400 hp range. Above that, its on borrowed time in my opinion.

You could dyno and horse around a little close to 600rwhp, I'm sure. But drag racing in that range is probably gonna cost you.