I have switched to using the 99 ron Tesco petrol, been using it for about the last 3 months, also put in Millers octane booster on every fill up aswell, used to get a bit of pinking before in 5th when giving it stick on optimax, switched to the 99 & millers & no pinking. Thrashed the shit out of it at brands on a trackday & was fine.

Simon.