I just assembled a Wildhare 300 Extra with DA-50R. I bought a Bisson Pitts muffler and have been pleased with it. Easy installation and everything fits well. The only issue I had to deal with was how much to cut the cowl as that muffler really spreads out in area. I eventually had to cut off some of the pipes to get the cowl on. I did this very carefully in little increments. The end result is that the pipes now only extend about 1'' below the cowl but this is ok. Also, the Bisson comes with a smoke fitting already installed. I didn't use this feature so I removed it and plugged the hole with a small screw and it works fine.