2.5 hrs. on the firewall.

Starting the trimming to size...

I decided to use a clear plastic sheet as a template to cut out all the holes.

Taped up and ready to go.  I initially cut the center cut to correspond to the vertical channel.  I figured that would help to keep things aligned.

Putting in a few fasteners to further keep things lined up.

Then it was a matter of going around to all the places the shield needed to be cut.  Many...

Many...

Many...

Done and on to the heat shield.

Cut enough to take off the template.

And lots of cutting later...

A test fit shows this approach worked well.  Some minor adjustments and remaining cuts (I'll test fit the brackets again) and it should be ready to stick.