I just installed a 2 into 1 pipe on my 2010 Street Glide. Great looking and sounding pipe but may be slightly louder than I thought it would be. I got the wrapped perforated baffle. Waiting for the Zippers max flow air intake which should be here tommorow
The concentric is the quietest. They'll all get louder over time, but I wanted something I could spent 12-14 hours in the saddle with and not be deafened.