It's essentially welded in place, although you can drill the rivets out and repack it or make it longer, etc. So yes I do, PLUS I use the little B&S style muffler after the silencer.
Low cost muffler
Sound can be very subjective.
I think the expansion pipe alone (no silencer or muffler) is much louder than stock. Most will agree. Open pipe? Yikes, loud. But way difference noise.
With silencer, it helps. Not exactly quiet and probably most chicks will say it's louder. Need the dB meter! But it's about the same, just whole new sound, way different - like a nice revy dirtbike.
With silencer and muffler, it's quieter than stock IMHO. Yet some will still say it's not quiet enough. At this point - let's find out where most of the noise is actually coming from. Yep, you are correct - it's coming from the explosion in the engine itself - not the pipe. Thin aluminum air cooled 2 stroke engine is never going to be quiet.