I tested the (now) $180 1-5/8" Summit headers vs the TTI stepped headers a few year back. On a 600 HP 424"/360 there was a 1 HP average gain from 3,000-6,000 rpm with the TTI and a 11 HP peak gain at 6,400. Not worth the extra $500 in my book.
Thanks for this. I kind of felt the same thing when I switched over with my 410 from Hedman 1 and 5/8 with a 3 inch exhaust to a tti step header....it felt like 15 or less gained.
