Is there a "best" ROM for GPS?

[arizonaomnia]

I'm going to drive from Tucson to Denver in a few days, and I'd like the GPS to be working perfectly. Some days it works nicely, other days it is crystal clear in the sky and I get that "Weak GPS" error message anyway. Is there a way to "tweak" the GPS somehow? If not, is there a ROM that somehow enhances the GPS? Anyone have some advice here? I tend to use Google Maps or amAzeGPS, and I've experimented with both Windows-managed settings and the COM8/57600 baud option, with mixed results.