I am running the stock header and pipe. I haven't made any changes to it. You are right about the altitude here. When I would go to sea level to fly in a pattern contest I always tried to get there a day or two early just to set up my engines. It was like having a super charger on them.

I'm running Wildcat 10% with 3 oz of castor oil added to it. I'm probably going to mix a few fuels together to get about 12 1/2 percent nitro. NovaRossi is pretty stun on running 10% fuel.