Took our Stallion to a muffler shop and changed the exhaust. We took the rear cat and little OEM muffler off and installed a stock automotive oval muffler and what a difference. Don't know about the gas mileage but it sure is quite. Didn't really buy it for gas mileage anyway, just for enjoyment of touring around the countryside. Leaving for New Brunswick, Nova Scotia, Prince Edward Island, New Foundland/Labrador on July 22nd towing our Bunkhouse.