I have a set of each in good shape. The SS ones are very light compared to the stock ones. They do not have the same sound as the stock ones to me. My understanding is they are the same diameter tubes so no horsepower advantage. I will be using a Dansk banana muffler.

Thoughts

SS won't rust Mark .... ever, & if they're lighter, then you're "building in lightness" per the Porsche racing formula (as opposed to concerns over tone or sound) - so that's my 2 cents!

And they are the same diameter as stock.


Tom
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If it's the same diameter it doesn't really matter, weight saving would be minimal overall unless it's a race car.
Go with the ones you like the best.

The usual SS exchangers will fatigue and fail over many heat cycles. If they are not new at least pressure test them for leaks for safety sake. There have been threads on here in the past showing failed SS exchangers.

Brett

SSI Stainless heat exchangers have tubing with the same outside diameter as stock but thinner walls so the inside diameter is larger.

My experience is it make a difference.

Jim

The flanges that bolt to the head are way better on the stock HE's. There's probably twice the sealing surface, and they fit the exhaust ports better.

That said, I've never really had a problem with the SSI's, but I have seen a few with the mounting ears pulled off.

I agree about the mounting ears pulling off the SS. It has happened twice to me.

Splitting hairs. go with what you like best.
I'm running SS exchangers, but I also backdated a rusted out system from a '75.
I haven't any fitment or sealing issues. I like that they won't rust out. Both stock and SS are old and both can fail. Go with what you like.

Prices for the SS have remained constant the last 10 years so if you need the money, sell them. If you decide to go back at a later date it'll probably cost you the same to buy a set again. If you don't need the money, keep them as spares in case the stock ones rust out.