More power to ya… literally . Unfortunately, in California, unless you live near Newport Beach, 91 pump is our highest grade conveniently accessible. Not sure what that translates to UK fuel grade. A Lotus Exige engine builder advised I could go as high as 12:1 on 91, but an engine rebuild was only $5k at the time. I would’ve went for it had I kept the car. Mid 11’s is highest I would consider for a California driven 355. I think 12 is ok for 93 pump.
Yep, that's why I would go for the full noise Matsu engine, which has cams, timing, fueling etc to get that 500Hp