As for headers it is a personal preference. I have coated Dynomax headers on the 69 and I have been very impressed. I did not have to dimple them anywhere. I have coated Hooker Super Comps on the 75 and I did not have to dimple them anywhere either. I have heard pros and cons for both. I highly recommend getting coated ones no matter which brand you decide on. They will last at least twice as long and they will reduce underhood temps. As for mufflers, that would all depend on the noise laws in your state. In Missouri, they are pretty lenient with classic and muscle cars. As long as you don't run open headers, or try to street race, no one bothers you.