My limit is if I can't hook 2nd gear. Though BM3 allows you to adjust boost by gear, so that makes my limit a lot higher than if I didn't have that option. But I enjoy wringing out 2nd and 3rd to get on the highway so those are important to me. I don't drag race or anything so all out power isn't important, just fun and gapping people that aren't trying to race.
Also i don't want to have to run a heavy race clutch, so as long as stock or an upgraded OEM Clutch can hold the power, I'm in.