I'm not the greatest at this kind of thing, but I would look for a 2 channel amp that supports 400w RMS per channel, since your subs support up to 400w continuous at 4 ohms.

The Xplod is kind of a middle of the road setup I suppose, but I never heard anyone recommend anything Sony-related for car audio. The Rockford you showed us doesn't really fit your setup.

My advice is talk to a tech over at Crutchfield. Find a decent make and model of an amp that they suggest for your setup, and look it up on ebay and Google shopping. I did a lot of planning when it came to the setup in my Trans Am. I started buying more and more performance parts, and ended up cheaping out on a lot of things, including amps. No regrets, though. Good luck!