box build

So i have a pair of logitech z-4's. The system is great and cheap! over the years ive gotten into music with more bass, so here is my questions. Can i take everything out of the subs box and put in a new sub?, and how do you tune subs? Sorry im sort of new. Picture of the back of the sub. Is it...

just bought a single sdx 10 which will run off 300 watts rms at 4ohms, can anyone suggest an optimum enclosure size and type? I can go ported or sealed, huge or tiny, just want something that works well.