I'm no audiophile, but as I understand it having 6x9s in the parcel shelf AND subs (especially more than one) in the boot is a bad idea, because the subs are affecting the air pressure on the back of the 6x9 speakers so they simply won't sound as good as they should do.
Aside from that, I'm sure it sounds fine, although I personally wouldn't fill my boot with that much bass - I might go for a single 10", but I do occasionally want to put shopping and stuff in there...

I definitely would've posted
before buying all that stuff tho - not that I can see anything wrong, but plenty of people here might know of better stuff for the same kind of money.