I'm going to do it. The monsoon system in my Bonnie GXP is getting replaced. I'm putting in some Polk Audio Mobile Monitors in the front doors, Mobile Monitors in place of the 6X9"*, and 2 12" Mobile Monitor subs with a new Alpine dvd nav head unit and 1 Alpine 1000 watt amp for the subs and 1 Alpine 90x4 for everything else. Im using Planet Waves interconnect for custom length. The question i have is, with everything going, do i NEED a wiring harness for the new head unit. I dont use on-star and dont care about door chimes or even if the radio stays on with the key off. Can i just unplug the factory unit and leave it at that, tap into a constant power and a switched power and have it all be hunky dory?