2009 750fi, Has Muzzy dual exhaust Muzzy digi tune, and k&n air cleaner. A Shop told me that the its not getting enough fuel for the amount of air it's sucking in. Has good fuel pressure 45psi, comp. is 65psi both cyl. and vavles in spec. There telling me to put stock air cleaner assembly back on and it will run fine. Is this true? any suggestions?