subwoofer amp speaker

Ok, heres the deal. I have two Planet Audio AC15D 15's. They're 2100w and 1050 RMS. I also have two Pioneer 12's 1400 W Champion Series. I was previously running just the two 12's in my car with a planet audio 2600w amp. I have a 2006 Chrysler 300. The battery is already huge and underneath the...

Alright, you guy's have probably seen similar posts like this multiple time's, and I am fairly new here so that's why I'm asking. I'm in the market for a 21" subwoofer, budget is around 100-500$. I need to know of some good, high quality subwoofer's out there, just so I can have a list to choose...

So as weak a the speakers may sound I have 2 (2" 4 ohm 10 watt speakers) 2(4" 4 ohm 8 watt speakers and a 8 ohm 75 watt subwoofer. What would be the best amp to power those. Also I might be buying new 4 inch speakers being that they are pretty weak. This is the set up I have, I made it myself...