Heat/vibration is always electronics biggest enemy. Mounting a control box in the engine compartment is not the most favorable environment for electronics, and not conducive to a long trouble free life. I don't use my glovebox, so I remove the cardboard liner and mount an aluminum plate to screw the MSD box on and run the wires thru the firewall to the distributor. Been running the same box since 1986. If you want to get the longest life and reliability from electronic devices, put them in the most favorable environment that you can.