Joe Black has some great points of advice. Another member here is PBKID (aka: Peanut Butter-Kid; re-named from a previous harassment thread).

Peanut Butter-Kid works as a professional automotive audio installer at Best Buys. Perhaps he might see this thread and chime in as well.

Another source might be CRUTCHFIELD.COM, as their toll-free telephone support is awesome and they may have some advice as well on weak radio reception problems. I believe there are even antenna "amplifiers" which help boost radio reception as well.