The only wires you would need to run through the firewall are the siren wires and the hood pin wire. I didn't do either. I didn't want the hood pin on mine because I like to be able to start my car with the hood up. And I mount my sirens inside the car. ( I have 3 inside the car) The only thing a siren outside of the car does, is annoy the neighbors. But inside the car, thieves have a hard time concentrating when their ears are about to bleed.
For the lock/unlock, there is a white wire (unlock) and light blue wire (lock) in the driver kick panel. Actually, IIRC there are a lot of white and light blue wires there, so you will have to continuity test for the correct ones. (Set your DMM to continuity and put one probe on ground and the other probe on the suspected wire, then click the lock. If you here a tone from the DMM, then thats your wire.)
I mounted my brain on the floorboard behind the brake. If you have a universal bypass, (one that requires an extra key) I would mount that under center console by the shifter. You don't want anyone to find that.
I mounted my antenna on the windshield behind the mirror. The wire run is quite simple. Just tuck the wire into your headliner all the way to your driver A pillar. Remove the pillar and run it down to the bottom of the A pillar and remove that access panel on the side of your driver dash. Pull the wire through there and run it to the brain. No need to remove anything but the A pillar for this.
