So the S4's been to MRC for the stage 2 magic. The family and I are planning a trip to the alps at Christmas. MRC advised I need an octane booster for dealing with the lower rated fuel in Europe. Just after some advice as to what people use. If they boost up from 95 to 99 or use their super 97-98 and boost up. What if any is the harm if it boosts to high ie a 3 point boost on 98 giving 101? Millers do a 3 point one shot that I was looking at but the rating I start with may vary depending on the brand of fuel in france.