On a 400 hp 340 the 1 5/8 x 1 3/4 TTI headers were down 9 hp to a cheap set of Hookers. The TTI’s were down 13 to my 1 7/8 Hookers.
And they were down everywhere, not just peak power.
They both would have been down more if my lazy *** would had added some primary tube extensions and if I used 3 inch instead of 3.5 inch collectors.
I’m going to test them one more time when the engine is back in the pump at 395 inches and with a better cam.
I’ll also test the big Hookers against the Hedman Hustler 1 7/8 headers when I do it.
I suspect the TTI’s will be down 25. Maybe more.