Why did the manufacturer include these holes in the floor pans so that later you have to fill them in with the plugs like the one in the picture? My other question is: is it better to get a rubber plug or the metal one? And if I get the metal one, it is welded on there, right?

Thank you all.

 

No the metal ones are not welded. They are held in with seam sealer. I think the holes were there for passing things through during production. Like air lines or something. I don't think it matters what you use to plug them with, metal or plastic, as long as you get a good tight seal. If your worried about originality you'd want metal ones. They are not expensive or that hard to get.

 

The hole are there for manufacturing purposes. When the car is dipped it needs to drain.