I just got finished putting my first 500 miles on my new engine and Spec Stage 3 clutch...and now its slipping in the higher gears. I noticed it after being on the highway for about 50 miles that if I stomp on it in 5th or 6th it breaks loose...

is it a bad clutch disc? glazed? just really hot? I need to know whats going on...

 

Same thing happend to me, but it was a rear-main leaking oil. Maybe you have a small oil leak?