Dean Adams and others have offered skid plates for sale. While the stock muffler is designed to be a robust jacking point for the bike and it probably OK to take an occasional "rub" , remember its only held to the bike by the 3 thin straps. Even if you dont pierce the casing of the muffler, if you start to break the straps you could be in for a world of hurt, as it could cause the header (unavailable) to break over time.