I’ve got a bassbox in my boot, but because the BMW is quite well soundproofed I can’t hear it very well. It was making everything around the boot vibrate inside and outside, but not coming through into the cabin very well. After some research on TalkAudio and BMW forums it seemed that removing the metal plate spot welded over the ski hatch in the folding seat was the answer.

1. Cut the carpet off the back of the folding seat. You’ll feel a dip in the carpet all the way around the outline of the ski hatch. Cut the carpet off with a sharp knife. Remove the plastic trim from the edge of the folding seat to avoid destroying it.

Carpet removed ready to drill out welds

2. Some people say you can kick the panel out or smash it out with a hammer. I had no joy with those methods as the panel was very securely attached on my car! Punching the weld first with a centre punch or old drill bit stops the drill wandering all over and wrecking your seat. Drill out all the spot welds using a small drill bit first and then open the holes up with a larger bit. The top and bottom were particularly well attached so make sure all the welds are split before trying to smack it out.

Drilling out spot welds holding plate in place

3. Once all the spot welds are drilled, now you can prise and coax the panel out of the seat back with a screwdriver and big hammer. This took me a fair while, and the results were not neat!

The destroyed blanking plate!

4. It will need some cosmetic fettling to make it look nice and remove the sharp edges, but it got dark so I had to stop for the day. I ended up cutting off the flap of material that used to velcro to the panel over the hatch.

The finished hole - lines up nicely with the sub box port

Results are that the boot panels vibrate less and the bass comes straight into the car now. The sub box is on display, but all I have to do is flip up the armrest and it’s all hidden again. It would be easy enough to make a panel covered in acoustic carpet to cover the gap while letting the sound through, Next up is a better stereo (Alpine 9880-R) to increase the line out level and add iPod integration and sound deadening the boot to stop the number plate, bumper and toolkit vibrating!