What amp can I use to max out my subs?

I've got two 2010 12" Kicker CRV Comp VR subs. They each have an 800 watt peak power and a max of 400 rms (total 1600Watts, and 800 RMS) I'm running the kicker zx850.2 r amp on them right now with a 1200 Watt wiring kit being used. I've looked around, and pretty much everyone says that the kicker zx750.1 r amp will push them really hard, but that 750 watt amp isn't maxing them out. PS. I know that the amp is actually around 900 watts, because kicker underrates their amps, but 900 isn't even close to 1600. So what can I do to get the max out of my two subs? Extra Info: I drive a 2000 chevrolet silverado ext. cab, they are in a sealed box under the back seat. I listen to hip-hop/Rap music with allot of bass. I've got an alpine deck, and all my door speakers have been replaced with infinity's.