I just installed a system and it consists of an alpine head unit...with the head unit and type R 5x7s in the doors and no amp my lights on the hu would dim also. When the amp was installed it solved the problem. If you are planning on getting an amp i wouldnt worry too much about it until the amp is installed.

99 contour se debadged "knauberized" fog light mod 17" Enkei CDR9 225/45/17 Contiextremecontacts Alpine CDA-9807 and 2 12" Kicker Comp C12 subwoofers http://members.cardomain.com/ridered81