I apologise, I should have specified 'regular premium' rather than 'regular unleaded'. As I said, the performance of your engine relies on what its tuned for. If it aint tuned for 98 RON, I dont see how you could get a performance increase out of it. But hey if it does then go for it. My car for example, I switched to BP Ultimate once I bought it and Ive been getting power problems and pinging at low revs, therefore I'm putting it in to be tuned to that specification. Mind you being a jap spec engine you'd think it would be tuned for like 101 RON or something... What Im attempting to say is that when people say 'oh put high RON fuel in your car it will run better' I laugh...unless your car is tuned to accept and work with that fuel, it wont do jack.