Well, first we'd hafta know if it's a two or four stroke engine... if it's a four you'll get a reduction of backpressure & some performance increase & if it's a two, you'll get noise... and not much else.
Assuming you've a two stroke and you want better performance - don't even bother wasting your time w/the stock exhaust & consider getting a proper tuned pipe/expansion chamber for the thing
Everything ya ever wanted to know about exhaust & more:
Intake & Exhaust