Did some tidying up in my boot over the weekend.
Installed my Polk Audio MM840 into the parcel shelf, along with a layer of dynamat.
I used the included 5mm spacer, and made my own 2 extra spacers from an old binder. Its hard card, each 2mm think, so the sub is sitting 9mm higher than standard. Still hits the torsion bars, but not an issue, i dont think?
Following up from installing the MM840 into the parcel shelf, i got at removing the 12" boxed sub, and un-mounting the amp from the floor, and re-mounting it on the back seat.
Used a piece of MDF which i sprayed black, and screwed this to the steel support for the rear seats. Then mounted the amp to this, and run all the wiring either under the back seat, or hidden under the parcel shelf. I can finally remove the boot liner, and access the spare tyre, as the amp was screwed down preventing this.
Subs:

Spacers:

What the boot looked like before, PLUS of coarse a 12" sub in there too:

Then after removal of the sub, and repositioning of the amp:

Sub wired from the top, all nice and neat:
