1.How does everone keep the compression up on their l98s when switching to aftermarket heads?

2.Are the stock pistons dished in an L98?

3.I also wondered how thick is the stock head gasket and can you get any out of a thinner one?

 

Talk to Air Flow Research. They can help you. I'd vary the compression by changing the cc of the head since you are not taking the engine apart. They have charts on what your compression is stock (9.5:1) and they can calculate what your head needs to be to get it to a certain compression within certain limits.