Well, what I just did, was 2.5'' turbo-back and left the stock 2G turbo muffler on (there's only 2 slight bends: Down-Pipe, then @ muffler). 'Bout as straight rail as what most skaters would die for, lol.

You could possibly find someone who's parting with their 3G GT V6 muffler... I tried for that, but buddy already threw his out.