Whilst hunting for the appropriate petrol Performance Golf before I selected the R, I also tried a GTI sans PP and a GTI with PP in wet conditions. Under hard acceleration, the GTI PP had hardly any wheelspin, whereas the one without PP did have quite alot. Needless to say, the R was the best in this respect, with no wheelspin.
All three cars had 18" wheels shod with Bridgestone S001 tyres.