Well I would think a 9x8 APC would turn up pretty well on there... If you want a little extra power the Tower Muffler is $15- if you want more tha that, but prefer bolt-on horses, try a Jett-Stream Muffler or Ultrathrust muff. if you like the full shiny customize-able pipe, a MACS 7.5CC tuned pipe will get you happy-

I would keep an eye out for a Jett-50 on sale in the swap-shop or on Jettengineering.com This combo is guaranteed to kick some booty- (Then you can try pylon props. or just an APC 9x9 [X(])

Keep us posted!
james