Can't assure there was any fuel filter change, and hardly the injector was ever cleaned, however can't relate those to this specific behavior. Engine start and idle is very consistent. Nevertheless, we both have quite similar bikes and my buddy's bike noticeably pulls less strong than mine. It vibrates less but feels significant weaker. Final drive ratio on his (15/47) is a bit longer than mine (14/45), but from my knowledge this difference wouldn't make his bike so much weaker than mine.