I replaced my 09 Ninja 650 with a 14. I had a yoshimura on the 09 that i loved which is why i choose them again. This system is awesome once you remove the baffle (1 screw). Loud but not too loud. I do not have a power commander on the bike. It does backfire sometimes but only when its in second gear and you've had it wound up and letting the engine break slow you down but not always. Other than that no issue. Super deep tone. First day out i received a number of compliments at stop lights and in store parking lots. Assembly is easy. It only took me a little over a half hour with an extra set of hands. Minimal tools needed. Assembly can be done with a screw driver, hex keys, and sockets. Not to mention i could also notice a weight difference while riding surprisingly. The stock exhaust is a big heavy beast.