If you can weld, cut the flange off of the old muffler and weld some pipe to it. I would use a muffler of some kind, only because it will need a little back pressure. There are some really inexpensive mufflers at your local hardware store that will be just fine. I think i paid about $6 for mine. I didn't put it on a 97cc. I would really like to play around with one and see if I can't get it to perform well (not like a racing motor, but just well enough to make it useful). I will be drilling my jets and putting an aftermarket muffler on mine. I have an actual Honda 97cc motor that was left for dead, and I might try to combine them to see what I can do. I've got 3 97cc motors, so I have plenty to play with.