Hi there. Apart from the pictures you've seen on my350z, is there a real desire for 7 x 8" subs? If it's been done and budget is open ended, I would say do something completely new....
If you're going with that many subs, all it is likely to do is play one small range of frequencies very loudly. And 8" subs (with maybe the exception of the JL W7) don't shift enough air to give you the lower reaches of bass at the required volume / accuracy.
I would invest the money in doing something trick up front, and get it sounding good. Then once you have chosen that, the making it bling is a lot easier. Considering you sit at the front, why put 80% of your budget in the furthest part of the car from you??
My install is a stealth one this time round, and I think it sounds good. It's picked up a trophy in year one and a few members on here seem to like the sound too (which is nice!) and only uses one 10" sub and a pair of front speakers. And it can smash your head to bits if it needs to!
Seriously look at the budget and remember the car needs a lot more than equipment. You will need soundproofing and decent cabling. This WILL make a HUGE difference. You can spend £50 on a pair of speakers and install them well and they will embarrass a pair of £200 speakers badly installed.
Hope this helps