I had a stock 225 slant six exhaust on my 1964 valiant. I need a new one and I just cant seem to find one that is better than my old one. I need like a list of places to go or something.
You might do a search for Clifford. They specialize in 6 cylinder stuff. Don't know if they offer a complete exhaust system or not. You might also ask over on www.slantsix.org
Clifford's customer service has gone downhill in recent years - to put it mildly.
If you aren't contemplating headers, just take it to your local hot rod exhaust shop and have something custom made - nobody makes a real bolt on kit for the pipes for these cars anyway. Doug Dutra builds an interesting split manifold if you want a true dual exhaust setup.
My plan is to just take to a local shop and have one made. It still has exhaust on it so the shop can follow where it should go. I plan on some sort of turbo muffler for a little more bite sound.