I have got a old unit from them its a serial port type
I had problems getting a lock in my car - I kept moving it around
and no luck - I thought about that it had a magnet, and got a flat
piece of metal - I stuck the GPS unit on top and BAM I got 4 to 6
sats locked
I have it mounted under my rear window as close to the glass
as I can - its under the carpet on my rear shelf mounted to a
square piece of metal - the metal is about 5 inches square
If you can some how replace the antenna you could try this but
its ugly
An Inexpensive External GPS Antenna - PDF download-
and here is some links
Links to GPS Antenna Construction Sites
Good luck