[Sectorsteve]

i pulled stock off recently, then put it back on as my after market wouldnt fit right away. The next time i rode it, it sounded different and didnt have as much pepp. Could also smell gases from the engine near header pipe. Chances are, if you moved a muffler or something you may have disturbed the header pipe/head connection. Seems pretty common. My gasket was stuffed as well so i needed a new one.