As above. Mine was missing when I bought it and the noise is giving me a headache!

I had the same issue but I just bought a roll of foam mat 1cm thick and glued it in with 348103 - EVO-STIK - IMPACT ADHESIVE, 250ML | CPC.... Two layers of that mat matched the sound proofing of the passenger side mat and cost £10. Once the normal driver's side top mat goes in you can't see it anyway. I then went on to cover the entire seat box and van back using the same stuff..... wow it's quiet now.

Its going to be loud anyway, its a big hollow metal box,

i found on top of soundproofing, new stereo and speakers worked nicely