I personally liked the sound of the M4 but it looks terrible, so I decided to go a complete custom route. I now run an R6 header but I don't currently have pictures with the r6 header on the bike. Here's a few pictures so you can get an idea what I did. I had an exhaust shop custom weld from where I chopped the stock muffler off, which I believe was almost a 4" opening down to 1.5" so I could slip on which ever muffler I wanted on. The sound from the Yoshi is one off