I use the Aerotrend silicone tube with an OS 52FS on a Morris the Knife. The tube is 12" long and diverts the exhaust to the underside of the fuse. It makes a huge difference. The only mess in on the underside of the profile fuse and a little on the rudder.

Although Aerotrend says not to use the blue silicone tube with 4-strokes, it works for me. The silicone does cook a little at the muffler. When it starts to crack (after 10 to 15 flights) I simply cut 1/2" off and re-attach it.

Jason