I never had an probs with slipping running 8 or 9 psi. Even when the motor blew at 11 psi, the clutch was still grabbing very well, no slipping. From what i have seen, going upwards of 13+ psi, your stock clutch wont last long, or will start to slip then wear out quickly. I'd say a questamate of power to be in the 250-275 HP range for the stock clutch. Stage 2 boost levels, you will be fine for some time, assuming you dont abuse your clutch and it has been treated well, with less than 75,000 miles on it. Higher milage will mean it will not last quite as long.