Ok so i got a suction cup iphone mount the other day, just to find that the cupholder does not hold air very well, any ideas how i can mount it in the cupholder?

 

I know this doesn't really answer your Q re the cupholder. But, I installed a dice integration unit in my TL, and I just ran the connector through the console, so the iPod connects and rests in the upper compartment of the armrest. Works great. It's out of sight, and I control it with the stereo controls.

I did the same in my old '05 Jetta GLI, but I used a panavise mount that fit perfectly on the right side of the dash console, so I could see and control the iPod, but it was out of the way. Clean.