I bought the exhaust system for a 65 Mustang, 302, Hedmans, and 2 1/2". The tailpipe part fit fairly well, the H pipe worked out, I dumped the Summit ball type connectors for true Hedmans. The pipe from the H pipe to the headers was a total pain in the a$$! Luckily I have a MIG, a Sawzall, a heated shop, and a fair amount of patience. I did finally get a respectable install out of the deal. On the other hand, I also have a 68 Camaro and put the Flowmaster American Thunder system under it. No problems whatsoever! It took probably 1/4 the time or less to install and the fit was excellent. My Camaro also has Hedmans. If I had to do it again, I do think I would go with the Flowmaster system even though I have never installed one on a Mustang. A little more money, a lot less headache!