Actually, hardware store, clear silicone works as well as anything else. People do not believe that, because of all the hype advertising on this color and that, but clear will do everything you need. The exhaust ports on the race car had been relocated and there were no gaskets made for it, so we would simply seal the headers to the heads with plain, old, clear bathtub silicone. And it worked a treat.
Sure, that magic, reddish-orange stuff would work, as well. For about 6 times the cost. You can buy a caulking gun and a big tube of clear for the price of a wee tube of the super-duper, ultra-trick, double-throw-down stuff.