Heat in Cabin---do these holes get fender plugs?

[StevenF]

In one of my previous posts, I mentioned that I am getting  a lot of heat under the drivers feet.  I am going to insulate under the carpet soon but when having the car on the lift I noticed 3 areas where there are no fender plugs
I have attached 3 pics that show holes in the local area of the drivers seat.

Do they get filled with Fender plugs or are they left open for a reason?

Regards
Steven

[Cees Klumper]

You definitely don't want any holes in the firewall, not so much to keep heat out, although that is also relevant, but engine and road noise. You will be amazed at how much quieter your car will be once you plug every single hole into the cabin.

[StevenF]

my only concern is that those holes are for drainage...I dont want to block them up