LOUD LOUD LOUD Fit and finish were excellent however I did not use the spacer they provided for the canister. It was a bitch to line up and after measuring the space to the tire I decided I did not need it. The inside of the pipe was described by FMF as having a tapered diameter in the canister. As best I can tell it is a big honking hole straight thru. The end cap that makes it an FIM model is nothing more than a oval cover over a 1 & 1/2" circular opening. I ordered the optional spark arrestor which you have to totally remove the circular end cap to use. With the stock set up the bike was actually louder than with the spark arrestor installed. I can not find a picture of there quiet core insert so I do not know what direction I will head in now. I did not weight the stock muffler but there is a huge difference between the FMF and stock. Just for the weight savings I will probally keep this set up and buy the quiet core insert for when I need it.