best speakers to put in barracuda ???

ive got a spare cd player in my garage, so im going to stick that in my barracuda,

instead of disconecting the original radio, im going to wire the cd player up from scratch,

my idea was to make a box to put in the boot and put 4 speakers in it, instead of cutting bits out in the car, so put some speak wire to boot,

but what would be the best speakers to put in, all the sound is going to be coming from the back. i dont have a clue on sound systems, i live in the uk so something over here what would be ideal, i dont have a clue what im looking at so if someone could show me the best one's to buy,

cheers