Alarm system now finished, central door locking and all!
When the doors lock there is a reassuring mechanical 'thwump' as the actuators push on the interior lock bars! Added bonus, I cut the spare garage door fob open and soldered in some extra wires so now the accessory button on the alarm fob can open and close the garage door. Also, under the dash is a button to lock both doors should someone try and enter the car while I'm in it.
Wired a cb radio into both the Challenger and my Brother's Camaro so can communicate while out cruising. It all installed rather neatly, I can reach the glove box from the drivers seat to operate the CB head unit and the handheld radio and coily wire fits into the central ash tray. So aside from the clear antenna stuck to the passenger side of the front windscreen there is no evidence of the CB from inside the car!