Phil (interloper) is 100% right. Shell100 is an ethanol based fuel, ethanol burns faster, which causes the fuel mixtures to go LEANER. So unless your ecu is tuned for ethanol it will be slightly learner, which is not ideal for track use. If the ecu is tuned for ethanol, the fuel will definitely be beneficial and also reduce the likely hood of knock.
If your car is tuned for the premium 98RON fuel, just through in a bottle of GOOD octane booster, as a safe guard.