This is a message I got from Brian about my M&K.
Jerry,
The muffler you have is an MKM26 dual out sport muffler. Either side can be capped. The only change in sound volume will depend on which side is capped. Cap the driver's side and all the sound comes out the passenger's side which of course will be a little less loud for you in the driver's seat. We have internal caps that slide inside the tailpipe stub-out and are then captured when the tailpipe is bolted back on. That also allows you to retain the dual out look.
I bought the car chemistry inserts and they do help. I don't have many miles on them yet. I did this toward the end of the driving season last year.
