As others have said, loosen up on the bars, keep your eyes on the road and look ahead through the turns. Ultimately the trick to this sort of decent is to learn how to do it fast and to stay assertive, get out and take the lane.

By the grades that sounds like a 40-50mph ride depending on a few factors, maybe more. Today my descent top speed was 48.7, at at one point I remember actually thinking its MY lane. traffic on this road is 50-65 and I spent the whole day hugging the fog line, but on the descent that's too dangerous.

Also don't think about what can go wrong, when it comes to anything with this level of danger, you have to know you can do it.