does anyone know of any good dh tracks in the auckland region?

check out http://www.akdh.co.nz - they're the best club in the Auckland region for DH. And in terms of tracks, you're probably looking at Dome or Riverhead, unless there is still stuff out Muriwai way...

As Jono said.

Check the website, we have a "where we ride" page.
Also keep watching the Calendar. We try to have Shuttle days on the third weekend of the month. Currently alternating between Maraetai and Dome valley.
The next shuttle day is the 28th (I think) of Oct. We'll be shuttling the new track at Dome that's going to be used for the NIS final in December.