I mounted the brain box for the Lightspeed ignition system to the starboard subpanel rib. The power and sensor connectors face aft, and the ignition wires exit towards the front, where they have a straight shot through the "noisy" firewall passthrough. (The "quiet" passthrough will be on the other side of the airplane, where all the sensor wires will go)
I used some z-channel material I had laying around, and the box is attached to the channels with screws. The lower bracket is riveted to the avionics shelf, but the upper bracket is attached with screws. I did this to facilitate future maintenance, since I will be able to get to the lower mounting screws from underneath, but the upper ones will be pretty much unreachable from down below… instead, I'll reach in through the forward skin access panel and unscrew the whole bracket from the rib if I need to remove the box for repairs.
