Odds are good your exhast leak is coming from where that rear header connets to the motor. Take off the covers for those cylinders and start the bike to see if you feel air being pushed from either side. If i remember right, theres a clamp back there that holds the pipe to a fitting thats bolted to the head (been a while since ive seen a stock exhaust). If the leak is there, you might need a new clamp, and/or theres a bent mounting tab for the exhaust thats pullings past what the clamp can handle. Its possible too that it could be coming from where the cans connect to the headers... id be more inclined to check up by the rear head though. Congrats of breaking your addiction! An old friend of mine just came out of a year long coma from heroin... i know the carnage it causes and the pain it delivers from seeing what its done to him.