Another thing to think of is everyone that I know of who has switched from the 1 7/8" TTIs to the Hedmans has picked up,some as much as 2 tenths. I think that is due to the fact that the TTIs have a 3" collector vs 3 1/2" for the Hedmans and the Hedmans are better designed as a race header. I ran the TTIs on my last combo.