I put tecno hunter on my newport. i expected it to be louder than stock, of course, but it was quite a bit louder. One of the positive things about mopeds, for me, is that they are unobtrusive, non threatening. I appreciate the fact that i can jump the cue of cars and motorcyles wherever i go, lean the ped against a tree or even a bike rack, and am met with nothing but smiles. you lose that freedom almost entirely with a loud pipe.
I tig welded a small riding mower muffler to the rear flange of the pipe. Made sure it was tucked up close to the frame and painted flat black, its nearly invisible unless youre looking for it. huge difference in sound. no differece in performance that i could tell. the add on muffler was designed to ventilate up to about 500cc on a mower so for the e50 its basically pass through in terms of back pressure.
I tried the little hot dog shaped push-mower muffler first of course. Four bucks, common as dirt at any hardware store, 1/2 npt threaded end. It did nothing at all for quiet. (edited)