RE 8's

the re's will sound damn good ported, you'll want to give them about .5 cubic foot of airspace tuned to 32 hz for sql. four of them would sound really good in that enclosure, I've heard two of them in the same enclosure and they sounded pretty damn close to a couple of 8's.

to everyone else on here, I have heard 8's in a properly designed enclosure sound pretty damn close to or exceed some 12's of the same number. It's all in the install, there is an ID dealer here in town who is running 10 IDQ v2 8's in a ported enclosure running off of lunar amps and those 8's get ridiculosly loud and sound real damn good doing it too. And yes they sound really good and clear, he competes in sq not spl and I've heard his setup embarrass people with the same amount of 12's in their setup. Again it's all in the install and design of the enclosure.

You can get some 8's to give you a pretty nice sound but it all depends on your music listening habits.  If you like it real loud all of the time you might want to consider a larger driver.  4 8's might give you the sound of tens but you will encounter the problem of sustained power. 

Because a speakers RMS is 200 or 300 RMS this does not imply that the driver will keep working at this volume for long periods of times.  Just like an engine a driver gets hot, and with too much heat you encounter thermal breakdown or in a speakers case voice coil burn out.