Just an FYI. I have a friend that owns a 2017 GT350. He put headers on it and an aftermarket x-pipe. One of his mufflers developed a "rattle". Car had approx 2200 miles. Ford denied the warranty on the muffler because of the exhaust mods. He did cut the muffler apart and find 2 spot welds were not correctly welded by the way. The replacement stock mufflers are about $900.00 a piece he said. Now I think that the dealer stepped up and use discretionary funds , but still Ford sounds like they are not messing around. By the way he put Borlas on it and it sounds killer!