Just got my Sabre a couple of weeks ago and love the power.I do have a couple of questions if anyone can help me with.There is some backfire when I roll off the gas.Sounds cool but the neighbors may get tired of it at 5 AM

Been told it is no big deal but now I think my MPG is suffering. Any thoughts?
Also I believe my bike has the CA emissions set up.Had I known,might not have gotten the bike but any how.......Can I safe and with little head ache change the set up to the Canada/49 state set up? Would appreciate any thoughts on either!