As a former installer myself, I would NEVER go to Best Buy or any other large retail chain that isn't totally dedicated to car audio and accessories. The product of course is the same, but the quality of their installers...well, I spent about 12 hours doing a COMPLETE re-install in my friend's R-32. He had the Euro-spec nav unit installed and a small amp for a sub. A pretty basic install in all honesty, but they managed to screw it up. I'm getting off topic here, but I'd go elsewhere for the install. The only thing to make sure they do is the 3second lock/unlock pulse. If I was at home (i'm @ work) I could upload the wiring diagram, which is very similar to a 5-wire system. We have vacuum locks, and the vacuum pump is activated by a 3 second pulse coming from the unit. These wires are in one of the harnesses behind the drivers side kick panel. Also, make sure they do the factory alarm arm/disarm. If it's done correctly, you can use any combination of key or remote to lock and unlock, and at the same time arm and disarm respectively. Other than that, our cars are super easy. A full install should take about 2 hours, start to finish.