couldn't find a link to that bike. Would like to see it. Makes me thing of the jing chen knights <sp> which were supposed to be really bad-ass little bikes.
do you have a local dealer or service center? from your post it sounds like you aren't fixing it yourself. Is there another name your bike goes by?
If I were in your shoes, I'd try to find a new performance exhaust. Assuming it's a 2-stroke. there's a lot of stuff available.
I don't know that running it with a leaky exhaust will hurt the engine (maybe the performance) but you don't want stuff to start falling off either.
if you're scared you bike is on its last leg, you might want to consider an overhaul (cheap $$ even if you don't do it yourself) or at least have it looked at.
depends if you want to ride it into the ground and have a rat bike to beat on, or if you want to have a good ride for a while longer. Didn't you post about 'chinese crap'
did the dealers hassle you? that sucks, I know. with the cold weather, if you have a place to work you could fix it yourself..... cheap option.
post a pic or a link to your bike... I'd like to see it. Is it a sundiro? sorry i was slamming them, different class of machine, and I'm in love with my current scoot.