[@wot]

If you are building an engine that will run on 93 octane, you need to cc the heads. Otherwise, it really doesn't matter what the compression is. If the engine is detonating (you hear it or check for signs on the plugs), you need to make some tuning/fuel changes. If your engine is in sound shape, and you like the timing and distributor curve the way they are set, you need more octane to resist burning too quickly in an engine that detonates. You may get away with lower octane if you are not driving hard

I have not had real good results with boosters, and still mix racing fuel with 93. The ratio depends on the ambient temperature.