So in Hallett this past weekend, I saw some really fast 250's on the track and I wanted to make sure I understand the rules, on exactly what can be done to the motors in the E Super Stock Endurance class? It says head gaskets may be replaced with any brand and do not need to be stock spec, as well as machining of gasket surfaces, etc. etc. It mentions the compression ratio must remain stock except where mentioned above. So does this mean, the compression ratio must remain stock unless you have decked the head or used a smaller head gasket?

It also says you cannot over bore 1mm unless sold as a maintenance kit by the manufacturer? No porting and polishing of the head, correct?