they are from a company called Megan Racing. They are not as smooth and will not deliver quite the power increase that Greg D's will. HOWEVER, many are using them. Some have reported fitament issues and some have not whatsoever. I am considering purchasing some myself just because I can not afford to shell out the additional money that GD's cost, and I will be plenty happy with the performance gain from the Megan Racing pipes. To me the few extra horsepower is not worth the extra money.