With 91 octane fuel and stock ECU, I was doing low 13s at 15psi. I made about 20 passes at strip, engine never detonated. To me water inj. did miracles. Still does. Am boosting 18psi now with ash ecu and water injection on 91 octane fuel. Don't listen to NIXIT his system does not even work and he invested $1000 in it. what a loser.