I spent some time today re-reading the installation manuals for the various MGL products, and I saw a diagram advising against placing my SP-4 AHRS on the sloping floor of the cabin, which I had done. My rationale was that the floor was fairly flat in that location, but when I brought out the digital level today and compared to the longerons, there was a difference. My remedy was to make a slightly sloping shim that I put between the floor and the rubber insulation. I now believe the AHRS unit is level. I also read consistent advice to avoid routing sensor leads with HT ignition wires. Unfortunately, that is precisely what I had done. After some re-thinking, I drilled a new hole in the nyloil as far from the spark plug wires as possible. I then cut my heavy gauge starter wire so I could move it to the new bottom hole. I then routed my CHT leads and the oil pressure leads through the top hole (formerly occupied by the starter wire). On the engine side, I used an Adel clamp to hold the leads above the engine and sharp edges. Coming out of the baffled area, I bridged the bundle over to another Adel clamp on the throttle brace. Then it was a simple matter of coiling the wires and reconnecting things. I used small cable ties to temporarily hold things in place. Tomorrow I'll replace those with rescue silicone tape and re-solder on the starter lead.
CHT leads passing through a new location to avoid the spark plug wires
Separation between CHT leads, starter wire and spark plug wires across the gap from engine to firewall