Air line comes from behind the trim and is routed behind the sPOD's header panel.

I'd recommend routing the air line through the firewall to it's final routing and connection location, connecting it to your onboard air system, securing the line under the hood to keep it out of harm's way, then securing any excess air line under the dash OR cutting off the excess once you know the length needed to reach the air gauge. You can remove any excess air line at the air gauge end before connecting it to the gauge, but not at the end the end that connects to your OBA system under the hood.

Before drilling my hole, I picked a location that would be easily accessible to route other wiring when the need arises - wiring for an auxiliary fuse panel, CB wiring, etc.

I picked a location that was easily accessible from the inside as well as under the hood.

Over the years of installing electrical doo-dads in a vehicle, I've found that sometimes the needs dictate stuffing a wire through the fire wall from the inside out, other times I needed to start from the outside and stuff the wire in. This is why I chose to drill the hole low in the firewall, so I had easy, unobstructed access to it from the inside.

I removed the battery to see where the wiring would come through.

Based on what I saw under the hood, my preference would have been to get the hole up higher, but inside access would be limited since the heater blower would partially be in the way.

NOTE: If you remove the battery, remove it before mounting the terminal strip, otherwise removal will be difficult because the terminal strip bracket gets in the way.

During other electrical mods I discovered the battery can be removed with the terminal strip in place if you pop the main electrical center/fuse panel out of its bracket and pull it up out of the way and rotate it sideways.

If you use the optional relay bracket, which mounts to the terminal strip, removal of the battery will be virtually impossible unless you remove the relay bracket and move the electrical center as described above.

Why all this talk about removing the battery? I find it easier to route wires through firewall, cover the wires with split loom, tie the new wires in place with cable ties, etc., if the battery is out of the way.

Here's the hole.

I cleaned up the edges with a dremel tool and used some touch-up paint to cover the bare metal.

This photo shows the relay bracket installed with 4 relays mounted to it

Red and white wires along the bottom row of terminal strip are relay ground and signal wires: white = ground, red = switch signal to relay from the sPOD

Install complete!!

Several color options are available for lighting in the switches. I chose 4 green and 2 red lights.

The sPOD can be ordered with different style switches than the ones I chose. It can also be ordered without the air gauge.

Once I install more accessories, I will label the switches. Currently the only accessory is the on-board air compressor, which is connected to the switch to the right of the air gauge, switch #4.