We've bought a used muffler with 36k miles on it from Colaws RV Salvage, Missouri. 10389 Cimarron Rd, Carthage, MO 64836. Phone 877-548-2125. Paid $200.00. Maybe 2 years ago. Tried the straight pipe route and went back to original. Dave Atherton convinced me to go back to original. Intake temps are more consistent. Just look for a used with low miles.