Just chiming in here...
I successfully installed the JL XD600/6 amplifier in place of the OEM amplifier using Technic's harness. It was literally plug and play right. I only had to wire amp power to the battery (which was already in the trunk) and ground it.
Everything sounds great and I'm amazed at how loud the music can go. Can't wait to get some new speakers so I can really crank the thing.
2008 E92 M3 | 2007 Honda S2000 | 2001 Honda S2000 | 1997 Turbo Integra