ORIGINAL: w8ye
The ASP Red Head 108's came with two extra head gaskets to reduce the compression. Mine seemed to do well on 10% with just the one head shim that was in it originally.
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You know, I forgot all about that. Thanks for stirring the old memory. It makes me wonder why I never installed mine...
Oh, I know why. All I was using for fuel for a while was S&W 5% nitro, 50/50 synthetic/castor blend, so I didn't need to bother with it.