I'm running 490hp crank. Been on the stock clutch ~5000 miles when stock, 4000 miles modified to that level. Clutch has seen the track one time and I am hard on it on the street. Has held up so far, though. Add another 50hp, can't really tell you much, but I'm sure it'd last just the same. I know guys with heads/cam with nitrous on top that have the stock clutch and have had no problems. Until you need to replace it, I wouldn't worry about it.