What is this rectangle cut out for? How does this foam mount to the floor?

I'm thinking it would be better to make a rest out of plywood and carpet it.

Thanks.. BillClick to view attachment

Egr counter on late cars.

Coke smuggling area…….

I think 914rubber makes a subwoofer that fits in this space. I'm under the impression that something needs to occupy that space to make the carpet fit correctly.

David

There is a small piece of wood that fits in there. It covers the egr counter.
Craig at CAMP

It does look kilo size..