stage 6 motorsports or rainbow muffler. Stage 6 has a website and is a high end build/performance shop and rainbow is a muffler shop that welds. I got my exhaust put on up there at a place off sunbeam road and had a fix done at rainbow but I have never been to stage 6.
http://www.stage6motorsports.com/ Really not sure how good there work is but I would try them