Put a gallon of peanut oil in a nearly full tank of dino and your car will be much more quiet. It runs great and lubes the IP, and your exhaust smells good. IDI engines are the best to do this with; like the 616 and 617. Dont do it in the dead of winter, however. Sam's / Costco and other discounters can sell veg oil at near $2 buck a gallon.