I have built at least 10 customer cars , about 50% have used manifolds , the rest used headers , most have used TTi exhaust systems , most 2.5" some 3" for higher power applications , the TTi headers & systems are simple awesome & have lots of clearance for wires even with angled plug heads , they fit well , are top quality & sound great , 1 customer used the TTI exhuast & Hooker headers , the adapters from the hookers to TTi exhaust fit perfect , the fit of the Hookers is aweful though
I have made a lot of power through stock HP manifolds with the correct cam choice & careful porting