How far is too far? Coil location

I have my MSD blaster 2 coil on it’s side mounted to the top of the passenger fender close to the fire wall and the coil wire is about 16 inches long. My MSD box is mounted on the inside of the passenger firewall above the footwell. Don’t have any problems. Just make sure you use the same kind of wire for the coil wire as you are for the spark plugs. Before I took the heater box out, the PO had the MSD mounted to the air box right below the glove box.