Compression confusion

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Modern Ls engine use aluminum heads (which don't trap as much heat) and super efficient combustion chambers that let you run less ignition advance to light the flame. The more efficient chambers allow you to increase compression ratios without detonation, and that includes forced induction as well.
You could try to run 9:1 on an old 350 chevy with aluminum heads. If you want to limit boost to 6-7 psi then you can probably make 9.5:1 work. BUT you'll make more power with less compression and more boost.