sa-15 & x-15

I was looking to get a new subwoofer set up as the one I have is just not enough, currently I have two kicker cvr's with a kicker zx750.1 amp (birth sheet stats are 912 RMS @ 2 ohms) I plan on keeping the amp and ditching the sub's. Would I notice a difference between the SA-15 and the X-15...