I've posted a few threads on here about my bog in my 97 Ultra spx. I've figured out the bog from acceleration but now i notice I have a slight bog once i reach about 70mph. Once i hit 70 theres a slight bog some of the time, not all of the time, weird i know. My mechanic told me it cold have something to do with the aftermarket can. It was put on years ago and he said its a cheap one. The back pressure isn't right i believe he said. He thinks i should get a stock muffler and try it out. Its real tough to find one. Does anyone else here agree with what he said? He's been working on Polaris sleds for 20 years so i take his word for it i just want some other opinions. He said if that doesnt fix it then its probably the aftermarket clutch that's in it. The compression is good across all 3, and the jetting is all right.