Arrow Exhaust / PC V Installed

[uscgmac_imp]

There is still less restriction and more flow regardless of the cat being there. The ecu will compensate in open loop. Not so much in closed loop. The diffrence is not great but yes there is a diffrence and the air fuel ratio will change. Its much more prevalent with no restrictive cat and a after market air filter which will really open it up and make the bike run lean in which case you would need the fuel processor.