8 second difference is not too bad of a difference on the Ring, considering how long one lap is(23 km) and the fact that they were on different tires...I don't know which tire performs better on the track...the Michelin or the Pirelli ???

It should also be noted that they were tested 2 years apart. The comparison would have been better if done on the same day with the same driver and tires. I think the margin of victory for the GT2 would have been a few seconds less....