I have run the Tatone Peace Pipe on the RH 35... a stock one makes the engine run hot about mid-flight and the engine begins to sag. I trimmed the end (opened it up) and Dremeled the insides ... I did this to a OS Jetstream muffler too... the engine runs a lot better but still will run hot if you run it on the lean side. The Jetsteam ran great on an OS35s .. IMO, the tongue mufflers work just fine.. another muffler I customized for the Fox 35 was the OS 702, the front where it mounts to the exhaust needs to be ground flat, then I make a gasket with thick gasket paper and Pematex it to the muffler. This prevents it from sliding around and the sound is wonderful and no overheating... the trick is to experiment. Definitely make the holes point down, last year, I started flying again after a long lay off... and I mounted my tongue muffler with the hole up (brain fart) ... my hand was being burn while adjusting the needle and had oil all over it...what a mess..
JJ