The OS 35 is not a high speed engine but a nice sport motor and yes it too will respond to a tuned pipe but not as much as some other choices. Macs has the tuned pipe and header. Do not get the "pre-tuned" setup that the 32SX used because the header will most likely be too short for the 35. Ask for David and he can set you up. http://www.macspro.com/prodline.asp

If you havent got the OS 35 yet, I would get the Webra 36 (without muffler) and contact Macs for header, muffled tuned pipe and #9051 pressure fitting as well. http://www.swanyshouse.com/engines/engines.aspx It' a light, powerful engine that will fit the Kobra.

Put a 9X7, 8X9 or 8X10 APC on there and look out!

For the Webra use a 8X8 for break-in. Cut the header initially to 3.5" for break-in (measured from weld to end) , work it down in 1/8" steps for tuning later. Run at wide open throttle rich 2 two stroke (intermittent rich crackle) for two tanks. In Never use over 10% nitro in this Webra and the fuel should have some Castor in it's oil makeup. Use an OS genuine bubbleless clunk and "real" foam rubber isolated tank or use a bubbleless tank.

Have fun...