. You will not see the potential of a turbo or intercooler with pump gas. If you get high HP on pump gas, what does that prove? It proves that you are on the edge of grenading your engine. Is it worth blowing your $5K engine to save a few bucks on gas by buying 91 octane to get the maximum HP. It is like playing Russian roulette. I got 530rwhp on pump gas 91 octane @18 psi. My engine had three melted pistons. I heard no detonation .