The best place to mount for performance, is the center of the roof. Larsen makes a line of commercial grade antennas called the NMO series. It does require a 3/4" or 7/8" hole in the roof and uses a triple o-ring seal. This is the type of skinny 48" whip you see on police, fire etc.... The base is loaded and black is an option. You would have to get this antenna at a commercial two-way radio shop not a c.b. shop or walmart.

Here is a Quote from Larsen

"Correct antenna placement is critical to the performance of an antenna. An antenna mounted on the roof will function better than the same antenna installed on the hood or trunk of a car. Knowledge of the vehicle may also be an important factor in determining what type of antenna to use. You do not want to install a glass mount antenna on the rear window of a vehicle in which metal has been used to tint the glass. The metal tinting will work as a shield and not allow signals to pass through the glass."

Most people sh%* when you tell them about a hole in thier roof but it does make a big difference. I have been working in the 2-way radio industry for like 14 years now so I know this stuff well. When you go to sell your rig, either leave the antenna and c.b. or there is a rubber hole plug made specific for this. I have installed hundreds of these for ploice fire etc.. and have had no problems with water leaks. If you visit thier site, look for the NMO series in the low-band antennas.. Mike