I am in the process of installing a water temp gauge and a boost gauge. I have it all wired up in the engine bay and I running it through the firewall.

I can't get the cover off the wiring harness pass through area. I thought this would be the easiest part. I have tried just popping it off with sheer force but that hasn't worked. I have tried twisting and prying with no success.

Any ideas from someone who has accomplished this?

 

It has some snaps around the edge. Pry them outward and the round part will pop off easily. Not too much force is required, but it won't move till you pry the snaps open.

 

Here's what the cover looks like off of the car, and here's what's underneath it.