1. Remove the OEM vent cover with a bone tool or dull flat head screwdriver. Pry around the perimeter of the vent to slide it out. 

2. Remove the side dash panel. You can also partially remove this trim piece along the front of the jamb to get a better view of the defrost ducting. It is only retained by the weatherstripping. 

3. Place a rag in the defrost duct to retain drill shavings. Run your finger up behind the dash from the door jamb panel to feel for the defrost vent duct. It is thinner, slightly flexible plastic compared to the AC duct. Once you locate it, use a straight pick tool, or small drill bit to check your outlet location in the duct (white arrow).

4.  After verifying your hole location, Enlarge the hole to fit your wiring. Be careful to keep the drill at the same angle, and drill slowly. Check above the dash to make sure you will hit the defrost duct, not the AC duct. 

5. Run the wiring for your gauge up the vent hole then fish it through the stem into the gauge pod. If your gauge is hardwired, you will have to set the gauge in the pod first, then route it down behind the dash. 

6. Install the included adhesive pad along the edge of the pod. Most gauges will friction fit. If it doesn't:

1. The pad can be folded to make it thicker. 

2. Wrap a layer or two of masking tape around the gauge.

3. Use a rubber band on the gauge.

7. Insert the vent base at an angle to seat the edge closest to the windshield. It should be a tight fit. 

8. Once seated, slide the pod all the way back into the far edge of the vent opening. Ensure the back corner is on top of the dash surface. 

9. Press down on the vent slat edge. You should feel, or hear a click once its seated.