http://www.rcuniverse.com/market/item.cfm?itemId=797159

http://www.rcuniverse.com/market/item.cfm?itemId=798339

If you want to get better performance out of them replace the power robing stock chainsaw muffler for a after market and you will increase power output about 10-15%

Conversion kit $70.00
After market muffler $40.00

For about $300 to $320.00 you have a better engine than the Zenoah EI version

Milton