Looking to improve my Descent: Champions ranking... Any tips or pointers?

Hey.
Like the title says, I'm looking to improve my Descent: Champions ranking.

Currently I'm finishing just out side of the top 100 (which puts me in the top 10-15%) and I'm usually in the top 10 for the class I play (Duelist).

In the 40 mins of racing I'll usually hit level 20 and clear out most of the Inner Halls Level 1 but that's about as far as I can get.

Does anyone have any 'advanced' tips or pointers to help me push past where I currently am?

Specifically I'm interested in what items are the best to craft and what stats should I be looking out for on specific items?

This is the build I currently run with.
http://www.pathofexile.com/passive-skill-tree/AAAAAgQABS0G7iFgNDVAoF85YEthIWMXbml07XTxeu-E2YTvh2qQbJdwmSubLZ65qZS9gb6nwQfKkNRS137d4w==



If anyone can be bothered watching, here are some videos of my last few races. Just to give an idea of how I currently play.
It might make it easier to point out where I'm going wrong.

Path of Exile Race - 40 Min Descent: Champions (S08S104) (#5 Class. #125 Overall)
Path of Exile Race - 40 Min Descent: Champions (S08S108) (#5 Class. #111 Overall)
Path of Exile Race - 40 Min Descent: Champions (S08S116) (#7 Class. #128 Overall)

If you can't be bothered watching, any pointers are also very much appreciated.

Thanks.