Rosco- Internal combustion engines are air pumps. Moving more 12.5/1 charge thru the pump equates to more power. Not remapping or rejetting will fail to take advantage of the improved fuel air flow and will be detrimental to the engine as excessive o2 in a too lean mixture actually erodes the combustion chambers. DonĀ“t throw an exhaust system at the bike. Treat the fuel air system as a whole and you can pick up 25 hp for $2600 (1900 TiWorks 4to1, 400 PC-III, and 300 custom map). This will find the bike happily lofting the front wheel shifting from 2nd to 3rd at well over a hundred-twenty MPH.