Where should I put subwoofers in a truck?

Hi, so I'll be getting a 1999 Ford Ranger soon, and I want to redo the stereo system. I was looking at pioneer stereos from best buy, and speakers. Also dual kicker subwoofers that put out 1600W per speaker. But where should I put them? The truck's bed has a shell and a window that connects that bed to the cab, would they work as alright back there?
I'm new at this, but I've done a bit of research, pioneer and kicker seem best for the buck. What you guys think? Also what type of speakers would you recommend?

As soon as I saw ranger I already knew there would be a bit of problem. You have a lack of space behind the seat unlIke an s10 where there's room. You could most definitely put the subs out the window under the shell only problem is you will have crazy vibration in the bed of the truck. Even with a good built box it'll vibrate and make sounds too. I had two 12s in my toolbox and the bed made this annoying vibration sound. Pioneer and kicker are good but I'd also look at Sony xplod speakers too. These are all basic brands and go up in price but they're sold at walmart. They will still definitely do the job. I had kicker and they distorted in my dash. I installed sonys in my friends and at full volume no distortion. Pioneer I've had blown but if not wired to an amp they also sound good too.