Here's what I bought:
BRAND NEW! 47 / 49 cc POCKET BIKE RACING PIPE - eBay (item 300106518892 end time Jun-21-08 15:49:33 PDT)
I had a shipping voucher from my Paypal credit card, $29
Here's some shots:
Messing with my bike....new pipe/AC/chain guard
The supplied header needed some porting work and cutting it was interesting. Ghost0 is a 2-stroke power humper - his advice is gold. But being his stubborn business partner I always do something slightly different - I extended the front pipe to get more low end grunt.....neck snapping...just right and I can wheelie!!