Originally Posted by Jonathan Mormile
Buy a 4 channel amp and upgrade the door speakers with better quality 3 way speakers. Will I get alternator noise/interference from this type of installation? I was told by another stereo shop that they would not do this type of install because the speakers would eventually produce alternator or other interference noise
The primarily cause of alternator noise (or whine) coming from the speakers is improper grounding of the amp that is driving the speakers. A properly grounded (i.e. properly installed) amp should not give you any problems.
You will need a line out convertor to hook up an amp to the factory head unit...
http://www.crutchfield.com/S-RMR3s84...+out+converter