Viking provided a mufflered exhaust system when I bought the engine. It was simply a Honda muffler, probably off the car the engine came from, but the tubing and mount were actually quite nice. However, the huge car muffler weighed a lot and created way to much heat inside the cowling. It wasn''t long before I replaced it with a smaller straight-through glass pack. Better, but still a lot of weight and heat. I noticed, when running the engine with no exhaust pipe at all, it really wasn''t noisy, and considerably quieter than all the Cessnas around with 50+-year-old burnt out mufflers. I eventually just welded on a straight pipe and wrapped it with heat tape. Sounds nice and it''s as light as it''s going to get.