One of the cylinder head mods is going to be an upgrade to 1.6" stainless steel exhaust valves that are normally used on hotrod small block Chevy V8 engines. Thats almost 1/8" bigger than the original stovebolt valves, and with the increased exhaust duration of the CCS-1 cam, there should be much better exhaust scavenging, which improves volumetric efficiency.
Jerry

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