We've had a shed load of tests with 'ultra' fuels,the old Ford boys have done it loads of times as well and they only people that seem to get any advantage performance wise are Forced Induction cars,the Cossie YB powered cars saw an improvement,and as previously said especially the GT4s,JDM models in particular that have been run from new for x years on 102 RON over in Japan.Generally speaking you wont get anything from the 99 RON stuff in your n/a Celicas,other than the fact its a good fuel and the additives that are present in the stuff wont do your engine any harm at all