About 250, not absolutely sure it is hell scary at that speed. My mate in the back seat says it was 245-250. Ran out of gearing to go faster, engined pulled fairly happily all the out to this speed. This was driving between hometown and industrial town with excelent highways. That time was enough for me, won't do that again soon.
This is usually 4 hour drive. We cruised nearly all the way at about 180, anything above that my external wastgate was activated and was noisy and gave me the ****s. At one satge we had to stop (potty break), tried to catch up to cars that are allready going 150, not easy. Took nearly 15 minotes of 200 plus driving.
This road is well known for no cops, everyone speeds along it.