Whilst steve23002 was having some audio upgrades done at my house we got chatting about how the E36 saloon struggles with letting bass into the car if the system is not huge.
As I am not shy with a hammer I decided that Steve should have more bass in his car
Out came my hammer
When the liners are removed from the boot you can see a pre-moulded section in the centre of the firewall.
From the boot side I gave the spot welds a little tickle with my hammer and Steve now has more bass