I'm looking at either an 8 inche or a 14 inche shorty antenna from american muscle.com . Would either of those hurt my reception? anyone have any experiences with them?
The antenna on the car as it comes from the manufacturer is designed with a specific length in mind. The FM radio band runs from about 88MHz to 108MHz, with a centre frequency of about 98MHz. The wavelength of these signals is about 120.5-inches and the optimal length of a whip antenna for that frequency is a quarter wavelength or about 30 inches.
If you move the length of the antenna away from this ideal it's effectiveness will decrease. For strong signals like local, in-town radio stations you might not notice too much of a difference but you ability to pull in stations while on the highway will definitely drop, especially with an 8-inch part.
The stock one looks dumb after you see your car with a shorter one
I also got the shorty from American Muscle. My reception for weaker and far away stations may suffer ever so slightly but for the most part there is no diffeence other than it looks better.