I picked up my first bike a few months ago and the guy i bought it from had ditched the stock exhaust can in favor of a yosh RS-3 slip-on. Thing is... he went for the race can with a straight through design and i know he didnt bother to rejet the bike after. The bike is loud as hell which doesnt bother me but does the increased "breathing" ability of the engine call for a more aggressive rejet then a standard aftermarket slip on? Also, what kind of power gains am i looking at, assuming i through on a K&N to even out the airflow on both sides of the engine? Thanks for any help.