I ran just a Silencer pipe on ine and it ran quite powerfully.

RC SHowcase also just came out with wraparound headers for the ZDZs too.

Not to mention the AMT tuned pipes... they have a 50cc pipe and Dick has reported good results from these pipes (though I don't know if he has directly used one on a 50 yet) the 50cc pipe isonly 10 oz.... very light for tuned system...

Chips Quiet pipe would be a good choice as it's tuned, quiet and light... only 8 oz