I own a 2004 grand prix gtp. I put a system in this car but I'm having a major problem with radio reception. AM is non-existant and FM reception is poor to say the least. The reception was fine before putting in the after market system. My head unit is an Alpine CDA-9847. The grand prix has a rear glass mounted antenna. It should be noted that I did hook up power to the antenna and that didn't help. A car audio shop suggested I try some kind of antenna they put in hot rods (it mounted in the C post) so I had them do that and the reception is even worse now. I'm at a loss. Has anyone had any experience with this kind of a problem. Any suggestions would be greatly appreciated. The car audio shop also tried a different head unit and the reception wasn't any better.
Alpine units in general do not have very good Radio Reception. i noticed a huge difference in radio reception when i went from an Alpine unit to a Panasonic. ratings for your alpine are 9.3dBf, the panasonic i had was like 12.xdBf. a lot higher. not totally sure how that rating system works though. don't know if theres any kind of antenna booster or anything you could get...