TTI340BE-C4, 1-5/8" X 1-3/4" STEP HEADERS w/ 3" COLLECTORS. Im shortly going to a set of W2 heads which possibly need the larger, that said, I dont think this would be an issue, I havea good 3/4" clearance from the steering arms to any part of the pipes. My only complaint is I would not go flange headers again, they drag on everything, if i could gain a half to one inch there i would be happy, I dont want to raise the stance of the car but may be forced to. Mind you in this photo it doesnt look so bad