The system install was about $1100 at alberts cannington. Simon did it for me... he's really good...
Basically they took the firewall our of my back seat so the sub bass excursion comes through to the main cabin, and if you haven't seen the 310E before, it actually has two parts to it. The first is the actual unit which is 1DIN unit, and then the actual controls part is mounted into the back seat of my car cos thats where all the amps are. So there's a long cable run into the front of the car where it is mounted. Alberts ended up making an MDF slot that was covered in vinyl to crate a cover for the gab in the main console where the unit was cos there was a 2DIN MD player from the previous installation. I got them to flush mount the turbo timer above the head unit...
There were no problems filling the holes in the rear shelf cos they just used the standard speaker compartments and the way the amps are mounted it hides everything.
The second battery is under the false floor in the boot and is bolted down. It then has a cable running to the alternator to charge it while the car runs. I've also got an ACC switch that allows u to run the system without the keys in the ignition.
If you're just running the Unit with normal speakers and no subs then there's no need for a secondary battery, but if you're running amps and all you definitely should go for it. It's only about $300 for an oddessy one. In addition to that I've got 2 1Farad capacitors running in the boot. Basically you need 1 Capacitor for every 1000Watts of power otherwise you're system will brown out and you electrics could fail when u pump it, head lights dim etc. Capacitors store a residual charge and take the load off your battery.
All the lighting is just a 12" red neon light wired up to the boot light... in the cabin its just wired up from behind the cigarette lighter with a kill switch for when the cops are around... Turns off all the interior and exterior neons
Added some "making of" pics seeing that there's been alot of interest in the setup.
By the way my car is for sale if anyone is interested would be nice if anyone could let me know if they know of peeps interested in an R34.