To be honest mate there are very little gains from using 98 to 95. I doubt you would notice any difference for everyday driving unless you are racing I to a track.5th gear did a lab test on fuels a while back and there wasn't much difference in everyday driving for the extra amount you would need to pay for the ron98 fuel
I can definitley tell the difference between 95 and 98/99+ RON when tuned. The difference between Vpower and Tesco 99 is hardly noticeable though, imo.