Yeah, increase the size of your power and ground cables. For more than one amp you should be using 4ga from the battery to the boot, then you can split that into sections of 8ga if your amps don't accept that big a size cable.
I could try and find out for you, but it would probably be easier for you to register an account here : http://forums.nzicemag.co.nz/index.php and ask there. All the NZ car audio nuts are there, and there are even a few aucklanders who will do it for a box of beer, as long as they have the time.
I think you really should get a pro to check it out. Where abouts are you? There may be someone on here competent enough with sounds to check it out, or if not, an installer shop.
I don't quite understand how you are routing the cables. Are you using a splitter box for any of them?
Remote cables are fine to be daisy chained, but not power or ground.
Assuming they are SVC 4ohm subs. If they are DVC 4ohm subs then you'd need a monoblock that is stable to 1 ohm
Mono's are ALWAYS (BOLD RED LARGE FONT) the best to run subs on.
ALWAYS!!!
If you are missing a ground strap, then the engine won't even turn over. So if it doesn't turn over, put it on. If it does turn over but doesn't start, then it's not that.
And yeah its common to have a ground strap to a bolt close to the starter motor, under the top mount intercooler, passenger side.
Either that, or one of these for little spots - http://www.trademe.co.nz/Trade-Me-Motors/Car-parts-accessories/Paint/auction-252591586.htm
Contact panel beaters in your area, they may know if places who can make up custom paint spray tins. I know Total body Shop here in Wellington does, for about $35 / can
I dont know how much area you have to cover, but I'm getting one of these: http://www.trademe.co.nz/Trade-Me-Motors/Car-parts-accessories/Paint/auction-252591586.htm
Ring around some panel beaters, someone may know a place where you can get them made up. I know you can down here in Wellington (Total Body Shop in Petone - $35)
Either that or I can come get you, or take you home.. I live in Newlands after all. Is it the one on top of the hill just after you come off the motorway at the Newlands exit? I don't know the name.
I've also got a GFB Hybrid for my MY02. Can be run full recirculating, 50/50 or full atmo... the kit comes with all options.
PM the GFB guy on here and he can give you options for your model car