For a nice power boost check out the new Morris round pipe to FX conversion available at morris hobbies. This adapts the excellent rossi mini pipe to the OS FX. The power gain is phenominal. I seen a 1500+ rpm gain over the stock engine in most cases. The transition is very linear and fast too. More like a Webra or Rossi. This pipe is lighter than the stock muffler and clears the Flip3d wing better too. I used both a 12x4 APC and a 12.25x3.75 APC with excellent results in both cases. The cost is pretty pricy at 54.00 but it is worth it.