Does anyone know of a 2nd party antenna for the z1. I live in Whistler Canada (lots of mountains and furry terrain) and would like to install the antenna outside for maximum signal, but the z1 antenna is butt ugly and the wire is not attractive. Specifically I would like an antenna where the wire runs directly under the base so I can drill a hole and the base will cover the hole and eliminate any leak issues. My second choice is to install the z1 antenna under the bug deflector on the hood, it's a '05 Toyota Sienna van, will the hood slope affect the signal strength?

Drilling a hole in the roof of a brand new car?!?!? Why not just put the antenna on the roof in the back of the van. To my knowledge there aren't any aftermarket alternatives available.

If you mount the antenna towards the rear, coming out of the hatch, you should get great reception. The nav works off of satellites, so terrain isn't a factor, unless you live in a ravine or underground. If you can see the sky, the nav will work.

You know, I've heard that the GM antenna is usable with a mod to the harness. I think it's mentioned here...so you may want to search. But IIRC, that antenna has both the satellite and the GPS antennas in it.