Ok....thanks for the reply....that makes sense. I knew that if you added an extra gasket it would lower the compression, but I was asking myself "Why would anyone do that, that means less power". Now I understand it being about having a problem with detonating with higher nitro fuel. I will be using 10% and have already run the engine on a test stand. The engine runs great and now I know what the extra head gaskets are for. Thanks.