H/K questions. I'm a noob.
 

I've spent a couple weeks searching for information on the H/K system. I drive an 04 MCS and was curious about replacing the headunit. If I buy an alpine headunit will I need to run all new wiring in order to have door speakers? I tried searching and couldn't come up with a clean cut answer. Also with a wiring harness and dash kit what more do I need to do? I know I will have to replace the door speakers due to them being a 2 ohm. But beyond that I'm just plain confused...