that's a very good point, I understand that engine build affects max compression ratio. Let me rephrase.

I'm thinking specifically of a D16A6 combustion chamber, using 89 Integra pistons (big domes), to achieve approximately 11:1 compression. I understand that sharp edges are a no-no, and my funds a limited, so I'm thinking basically of a drop-in piston swap to raise compression to 11:1. Would 91 octane fuel be sufficient?