Hey guys new around here and was just wanting to ask a few questions to other owners of the good ol' breeze!

Now, im hooked on sound a bit at the moment (yeah yeah don't start :P )
And anyway, i have a sony headunit and just 2 kenwood 6 inch speakers running off that.. Anyway because i didn't have a clue about putting the 6 inch speakers into the door i just put them in 2 box's in the boot..
Now my question is, would the speakers fit in the door fine? Because i wouldn't mind chucking a sub in..
(don't say put the speakers on a parcel shelf because there isn't one)
Now! heres my other question..
I hear chucking the amp underneath the front seat is a good idea, but anyway i was wondering if you guys could recomend me what size and what sub and amp would suit me best? I don't want to spend alot.. So just want to get a idea of what i'd have to spend..

Thanks guys if anyone can help.. very much appreciated!