Last week, I had a custom exhaust system installed in my 75 F250 camper special. I went back and forth between a few shops and finally chose A1 Muffler on Barbur Blvd in Portland. Lee did a really nice job with the install, his price was very fair and he completed it in the time frame he expected.
If anyone is looking for a good shop for exhaust systems...check out A1 Muffler. I read their reviews on Google and there were 30 reviews that were very positive about his service.