Nathan
I have an 09 XB9SX and installed the Stage 1 kit from TwinMotorcycles. The guys over there are awesome and will answer any question you may have. Only draw back is that the system was a little pricey, and coming from the Netherlands it took a little while to get it. However I have had it on the bike for over a year and I love it. Deep sound from the exhaust with enough noise to show your present, but quite enough it won't make you go crazy while riding. I opted to have a new ECM tuned by them along with the kit so at any time I can throw the stock stuff back on if needed.