I have a 94 900rr and it came with a two brothers full system but was not rejetted. I have the jet kit but would rather my bike have the stock pipe for sound reasons (FTP) . Since it is not rejetted when I down shift it sort of makes a poping sound from the pipe, the shop told me it is because it is running lean when I let off the gas. My question is, if i leave the aftermarket headers on and put the stock pipe back on would it allow me not to have to rejet it..

 

i dunno about shifting but my bike pops a lil when i let off that gas hard from mid to high revs (deceleration pops?)

 

im assuming you are down shifting and letting the clutch back out right away. its just the bike "loading up". it happens when you go from a higher gear to a lower gear, especialy down a couple gears at once. its just un burnt fuel and exhaust igniting in your pipe. its common with bigger bore bikes, dont let the shop jack you out of $300.00 bucks to re-jet and dyno your bike. it wont hurt anything either so dont let them give you that line.