I purchased a 06 GTO from a dealer. When I let out the clutch slowly in !st gear and give it a little gas the car shutters. It only does this taking off from a stop. In any other gear or a rolling stop it is fine. Under full acceleration its great. I asked the dealer where I bought it to look at it and they told me it was an after market performance clutch and they do not warranty it. They stated it worked fine.