So, i picked up a used vance and hines ss2 slip on for a f3. aftersome minor mods to the ext. pipe, i got it all to fit very nicely. it is VERY loud, almost as loud as it was without a can. i am thinking that if it is that loudthere can not be very much restriction, should i think about rejetting the carbs?

 

You should probably do some test riding first. Is your throttle response crisp from about 5,000 rpm if you snap the throttle open? If so, you are probably okay. If the motor hesitates or stumbles, then you probably need to raise the main jet needle one 'clip'. You can use a couple of #4 or #6 washers stacked under the needle head if your needle doesn't have any grooves and an e-clip for adjustment (probably won't if they are stock)