Hi all thx for the comments so far. Re the sub box, I want to mount it on the sub box as I am aiming for a stealth install and if I mount the case on the sub box it can be hidden by the false wall shown in the 1st post. Its a custom job built for my car (2006 Mazda6 MPS / Speed) so it will be bolted down tight and be made of at least 3/4" MDF and possibly a little fiberglass). Is being made by myself and a buddy of mine who is a cabinet maker so we can brace and seal the hell out of it
For the case my ideal pc components at the moment are
M4-Atx PSU
Intel D201GLY2A Motherboard
1g DDR2 677 Ram
Sata 2.5" around 120g
Creative Sound Blaster X-Fi Xtreme Audio
USB Devices for Internet, OBDII, DVD, GPS etc
Thanks for the continuing help