I did the same thing on my old 73 Duster 340 about 8 yrs ago. It sounded sweet with a MP508 cam, headers, Ultraflows and full 2.5" exhaust with factory style tips.
What would you say was the first thing you noticed about the Ultras being on there?
I was told that they have so much back pressure that the "pop" when the gas has been left off. I have never heard that and the fellow that was telling me wasn't a very good source of hard evidence if you know what I mean.
