It Might be hard to find a good org one not rusted out
may be
Theres a guy in thornton greg who made a few for my bikes out of stainless steel for the TT500s pretty cheap and does a good job, full system $200 or so
but you have to supply a muffler if you want one
( Lilfords exhausts thornton hes a car guy but does bikes as well )
AND YOU WANT IT TO BE QUIET