I like your thinking sooty, V6s can drone fairly bad.
500pounds is a lot, where as here for about AU$1000 which is the same as 500pounds I could get a full stainless steal cat back custom made system.
I would love to get a BMW performance muffler but for 500 pounds i think that is abit steep you know, when after market would be considerably cheaper and maybe sound/perform better.
I will have a look and see if BMW Aus will supply me one, but if I get the opportunity to get a full system done by a custom exhaust fabricator for the same price as the BMW muffler then I may swing for custom.
I am just trying to get stuck in and really understand what options I have.
Thanks for your help and if you have any dimensions or specs on the BMW performance muffler that would be good. Is it a straight through muffler? Or does it still have stuff packed inside of the BMW performance one?