For a nice thump, a single 10" or 12" in a sealed box will do you well. Go for something around 400-600w RMS, and get an amp that matches the subs RMS wattage out put. Forget all about peak wattage, RMS is what really matters. You will probably have to build your own box to get the size needed by you sub. The sub should come with documentation stating the ideal box volume for ported and sealed, or you can look it up on Crutchfield.com. Sealed boxes require less air space, and so make more sense in our trucks. Also they produce a tighter cleaner sound, which really matter when you are sitting mere inches from the sub.
I currently run a 10" MTX Thunder 4500, Rated for 450RMS, pushed by a MTX TC2002 amp, bridged, rated at 425RMS. This combo works well together, with my home built sealed enclosure. I lost 2" of leg room in my standard cab, but achieved an almost perfect .98 cubic feet of airspace. I plan on stepping up to a 12" since my box is slightly bigger than I need for a 10".
I got my Jesus on the dashboard, but the Devil's under my hood!