I just bought a used 1998 FXDS-Con. It came with thunderheaders and it is loud. He also gave me the stock head pipes and mufflers. I went on a ride today and averaged about 50 MPG. If I put the stock pipes and mufflers back on would my MPG's go down or stay the same? If I keep the thunderheader on the bike I will have to rejet the carb I'm getting a lot of snap crackel and pop out of the exhaust during de-ecel (running lean). If I do that mod will my MPG's decrease or stay the same? I'm trying to cut down on the noise and still maintain good MPG's Thanks for any help on this.