I have been running without a muffler since the time it fell off, it isn't too bad with a full motorcycle helmet on and pretty quiet if I close the visor.
I recently changed my jet to 75 from 65 after I put on an open air filter that was initially resulting in no power at wide open throttle. It seems fine so far, problem is gone, but something feels off, might be 4 stroking, I think (need to listen more carefully before I come to that conclusion) I need to switch to 80 or 70, but it was pretty cold the day it was acting funny, I had to peddle up a hill that would usually awkwardly crawl over with the previous stock jet and air filter combo.
I need to deal with a vacuum leak before anything else, been riding with that issue for months now. It was initially the gasket which was fixed and one more leak I didn't bother dealing with thinking it's minor, it's the part the carb meets the intake manifold, the slits on the fins, got a Red rtv gasket, but it's not really meant to be used around fuel. It will reduce the leak which should better than now. I just end up using the kill switch rather than wait for the engine to take forever to idle.