I have homemade headers on my roadster (Chev 250)with 1 1/2" x 24" primaries into (two) 2 1/2" x 7" collectors into dual 1 3/4" pipes to 2" turbos back to 1 3/4" side-by-side duals to the rear.
I LOVE the sound! Mellow till you kick in all three rochesters, then it sounds like no other I6 or V8 i've ever heard!
Uncapped, it sounds like a slightly anemic hemi!