Jim yes they do the midrange ones seem to have the besthp rating through jet hots dyno testing.
gracing76 they are hooker headers with side pipes, got them direct from jet hot (the coating comp.) the entire set up with(sterling ceramic coated)headers pipes inserts and mounting kit was 1100.00 from jet hot, they were 1200 but if you tell them your from the corvette forum when ordering they drop 100. only mods are you have to lightly cut the rocker moldings to reinstall them near the front where the header comes out from under the car.

 

Or for the track, you can just take the inserts (mufflers) out and run them straight. Wicked sound.

Back in the day, we called this style of header/sidepipe combo "nest of snakes" which referred to the look coming out from under the front fender.