1 15 will surprise you. i had 2 ab 400.1s on 1 re mt 15 in my crx. it would really hurt you playing music. couldn't play it for long at that level. the sub did not like it.i had 3 cvrs 12s off of 1400rms and it really wasnt all that loud.
just got a 15 ssd and 1100rms and the FI blows the kickers outta the water.
Get one soild 15 and about 1200-1400 watts and u wont beleive the output u get