I bought a 2005 TTR 230 which has an FMF muffler. I ride mostly in populated areas and the muffler sound a little harsh. Having never heard or ridden a stock set up, my questions are: 1. is the stock set up significantly quieter? 2. Does the FMF really deliver significant power improvement (I don't race, just plunk around on trails). 3. Is it likely that the PO rejetted the carb when installling the FMF muffler? ie is it recommended by FMF? 4. Any body out there want to swap?