Start reading brotha...
http://www.bcae1.com/Topics are along the right side of the page, everything you could need is covered and then some.... Main thing you need to decide is what your after.... are you planning on being a bass natzi or are you after decent sound? What does the rest of the system consist of? Do you even have an aftermarket head unit?Are you amping the rest of the mid-high system? you REALLY need a plan... 4 10'z is going to overpower the rest of the system if you don't plan on upgrading that to (new HU, amp for mids-highs, other than stock mid-highs...ect)Overpower, i mean your not gonna hear it over the bass... not blowing things up... 2 12's will do the same or better than 4 10's using less space.... 2 12's "could" be put in the spare tire well, without much loss of cargo space... well, i bet 4 10's could to, it would just be more work... think of it this way 8 8" or 4 10" or 2 12" or 1 15" ends up all being about the same in terms of output, it's just there is a large difference in sound between each set-up.... 8's being real "tight" up to the 15" being rather flabby, in terms of sound...