That track is easily one of the most challenging in the world. Narrow, relatively bumpy, lined with slick grass and unforgiving walls, high speeds and large elevation changes. There's a reason that the great Jackie Stewart called it the "Green Hell". It still sometimes goes by this name, the "Grune Holle".
Driver makes a huge difference on any track, but on this track you need a true "Ringmeister" or VERY gifted driver like Jan Magnussen (who is the primary reason the Z06 got the time it did, with a Le Mans winning pro GT driver and full factory suppport) to get the best time.
If there are only a few true trials of testicular fortitude left in the world, this is definitely one of them.
Don't waste another minute waiting on parts, or anything else. Just get out there and start racing! You will suck at first, and you will be slower than many other cars, but the only thing you will regret is not starting earlier...