I have the tri-y headers. I run a 440 with 500hp. I run a 12.00@112 MPH with mufflers on. I am happy with them. I can probably get more out of my car if i went with better flow header like TTI. But i am happy with my car the way it runs at the track and on the street. Plus the tri-y headers fit a lot nicer to me, then the TTI's.