Help with Exaust

I finally got my mini ATV going (Quattro A4), but now the exaust sounds clogged or somthing and the tailpipe from the engine to the silencer turned RED HOT! I am guessing it needs replaced because it is clogged??

Will a cag exaust fit on a mini ATV (Quattro A4)?? If not, were can I get one?

Also, I lost a bolt for the starter... Where can I get replacement bolts that hold the pull starter on?

Thanks.