the header isn't going to be the primary noise difference... it will be the size of the piping... how much restriction of flow is in the piping... and the muffler that will make a bigger difference than the header itself.

there is very little difference between the 4-2-1 and the 4-1. Idealy for a top speed application you'd want a 4-1, wheras a 4-2-1 is more of a midrange power maker. It is rare that you will notice/feel/hear a difference with a header unless you have extensive headwork