I just got mine installed on the weekend. Came off a friend's car here in Asheville. Anyway, the power boost I get from this system is REALLY noticeable. Templar, who I bought it from, never had the axleback part that it came with put on the headers, instead, he put a Magnfalow on the back. The sound that my car makes is absolutely amazing. It sounds almost beautiful. I would say that this system is one of the best uses of money Ive had for my car. Its really an amazing system. I would reccommend either a gutted cat, or a higher flowing cat with these headers, youd be amazed at the difference it makes. The one I have is just a gutted stock cat.