What exhaust is better?
 

hy, im wondering what exhaust is better for piaggio ac 50cc (sfera). Stock old pipe that looks like boiler
http://shrani.si/f/16/Kh/44bx09De/sp2562.jpg
or

this chinese pipe that i have laying around from chinesse minarelli scooter?
http://shrani.si/f/1q/nZ/2qAuPYG5/prenos.jpg

pictures are from google.

I know its not a straight fit, but i can weld another pipe and holder on :D

Thanks for anwsers

Seeing the expansion chamber suggests that your scooter is a 2T and not a 4T. That said there's room for discussion. If you want stock sounding and normal performance stick with the smaller one. The other question is whether or not you see an improvement swapping them out. If not, go with the smaller one because all you're doing is adding extra weight which won't help you go faster and again, if you're thinking is using that on a 4T you're wasting your energy, expansion chambers really only help 2T scoots in specific power areas like top end or mid to top to give you that final kick in the pants to top end WOT. A 4T engine can't cause the back pressure to make it useful. The other side effect of having that weighty exhaust is control in cornering, IMHO the smaller the exhaust coming off the tire the better.