James;
Any muffler that fits a ST.51 and ST.60 will fit the .46 also. That will let you use a Scott Dinger or Randy Smith unit also. Both nice and light. As for props, look for some of the classic wide props from Rev-Up. I haven't run a ST.46 in a long time, but I recall that it was suggested that the best prop was a 12-6 Rev-Up cut down to 11 1/2" or 11 3/4". I have liked the Xoar props on my ST.60, so if you can get some of their 11-6, 12-5 and 12-6 props, they may do the job for you. Nice props and not too expensive. And don't underestimate the Master Airscrew prop in the same dimensions. They have improved their product quite a bit and the ones I have been testing on Fox .35s and such have worked well for such a cheap prop. I have several good ST.46s and hope to build something nostalgic for one, just for the sound! With a good muffler and propped correctly, you'll love the sound! I think they are just like the ST.60, in that when you have the right prop, it tells you! Whether they are competitive or not, it's fun to run and fly them for the sound!
Type at you later,
Dan McEntee