Well, I've seen a pretty fair amount of cars putting down 3-400 whp without snapping axles, but be that as it may, I've also seen a 180 whp almost stock GS-r snap an axle. It all depends on what kinda circumstances you're talking about. Just don't dump the clutch if you're running slicks, and you'll run a much lower risk of snapping something.

Erik is right though, it's better to have an axle snap than a diff shatter...or worse, an input shaft or something like that...

Later,
Aj