I have a 12g Nanocube. Im planning to upgrade powerheads to a Maxi Jet 600. My question is where would i place this new powerhead. The thing is huge. Also am i replacing the old stock powerhead or am i keeping both? Does anyone have a pic of how and where their powerheads are placed?

Im assuming its going to be your return pump youre upgrading. Thats located in the rear chambers attached to the output nozzle. They usually suction cup to the floor or the chamber, or just lay there. A powerhead is in your display, Koralia nano would work well in your tank.