Heres muffler will give 90 dB 9 feet 40146 running full bore over concrete slab Whats its quick easy build U Martin Dietrich HERE IS novel muffler Scale builders may find interesting made thin-walled stainless steel tubing installed along 05 46 EZ ARF Focke-Wulf FW-190 began using coping saw cut exhaust flange 1/16 sheet stainless steel experience indication can count breaking least four saw blades Next bent flex tubing hand silverbrazed exhaust flange opposite end closed off thin brass sheet soft soldered 45O solder large cooling surface keeps things quite cool high temperature problem large exhaust tube visible bottom reached upper wall inside flex tube hoping would reduce noise smaller tube does reach far used drain exhaust oil factory muffler weighs 33 oz holds 25 oz water Contrast foot 114-in OD flex tube weighs 42 oz holds 7 oz water Running full bore 12 x 6 prop 0S 46 produced 90 decibels model standing concrete slab nine feet sound meter 1992 47 stainless steel tube muffler attached 05 46 engine ready install authors EZ ARF FW-1 90 Running full bore 12 x 6 prop produced 90dB nine feet large exhaust pipe visible bottom flexible tubing reaches upper wall inside tube reduces noise levels smaller tube drains exhaust oil Scratch-built muffler compares favorably its factory-made brothers total weight sound reduction