[Dave at Pelican Parts]

The SSIs are roughly equivalent to stock. They are actually slightly larger inner diameter than the stock 2.0 pipes, which are slightly larger in diameter than the 1.7/1.8 pipes, so you might see a little gain. (And don't even consider the 75-76 exhaust for performance, it is terrible.)

You can help the stock HEs or SSIs a little bit by putting an 4-2-1 type muffler on, but the gains are still pretty small. Bursch makes one, and it seems to work a little bit but does rust fairly easily. Tangerine Racing makes a stainless muffler (!!!) that is designed to mate to SSIs and provide better scavenging. Not a real tuned header by any means, but knowing Chris Foley it should be noticeably better than stock.

Speaking of Tangerine, they do have a heat exchanger option for their headers. It's much smaller than the stock exchanger, so don't count on it for more than defogging the windshield, but it's better than nothing!

Other headers include European Racing, Triad, and Kerry Hunter. That is roughly in decreasing order of both price and performance.

I have seen a few other things advertised as headers, but they really were just merged pipes that bolted onto the stock exchangers and you could put a muffler on.

You might be able to find some used headers, but those are going to be taking pot luck.

--DD