Like TC, I have a stainless muffler from Patrick's. It's actually a Bazani. After I installed the headers, I drove it to the local exhaust shop and let them do what they do for $500. I think mine are 1 and 3/4 to the muffler, and 2" out. The sound is magic. They sing at 2200 rpm!
I also use water heat. I use a dual outlet waterpump and a bypass thermostat housing from a 261. I plumbed it with a heat plate and 5/16 brake line. It works. The difference in warm up time between this and exhaust heat is negligible. What I really like is keeping my new aluminum intake at a lower and more consistent temperature once the engine gets hot. I ran it for a few years with my original cast iron intake and it seemed to work just fine.
