hopin for a little help here, thanks in advance
just got my XG-550 a week ago. it runs pretty good, lots of fun to ride, but it has its issues.

I live in an apartment and dont have much access to welders, torches, or tool benches, so any modifications would basically have to bolt up with basic hand tools.
First, it's really loud I want to make it quieter without suffering to much power. can anyone suggest a silencer or muffler?
also, it feels like the speed flattens out way before it runs out of rev. I thought a bigger sprocket may help that situation, but which sprocket do I swap? how big should I go?
finally, (for now) I'd like to put a speedometer or cyclometer on, but I have no clue where to start looking for one that fits.
I've got a ton of my own mod ideas to make the XG Mine, I just need someone to point the right direction.
grinninfool