Has anyone installed one of these on their T3? I am wondering if it is possible to mount it directly to the factory rails without having to install the crossbars. I am guessing I will need the factory cross bars to ensure clearance from the sunroof?

Here are the measurements: 48" x 37-1/2" x 4"

The Rola basket appeals to me because the profile seems more slim than other brands, so hopefully less wind noise.

Rola Roof Top Cargo Rack Basket - $133.99

I, too, like the idea of a basket that drops into the roof rack channels - as you say, it is more streamlined, lowers the centre of gravity, eases access and simply looks so much better too!

See post #17 onwards in this thread:

Touareg TDI for Work? - Page 2 - TDIClub Forums

 

I think you will find you need the height of the crossbars to clear the opening of the pano roof glass...
The racks I have been looking at for my 7P (T3) are the Rhino Rack Platform Baskets
http://www.rhinorack.ca/AccSubCateg...cSubCategory_Wire-Mesh-Trays_Page_1_Accessory_Platform-Basket-Small_330_50.aspx
ultra low profile for clearance and wind effect, and will still let lots of sun ( and view) through the pano.
Also I have found with my landcruiser, platforms are far better for carrying odd loads.