Well I just got a very good deal on some car audio, and now i just need some advice on a subwoofer to get. Right now I have some Pioneer 6x9's (TS-A6970R) that I got for $20 from one of my brothers. A Kenwood HU (kdc-mp919) which has the screen that flips around, so its hidden when car is off, which I got for free from my other brother. And for an amp i got a Rockford Fosgate Punch 600aIV(600 watt), which I got for $50. And some eclipse door speakers (SE8355) that I bought at circuit city. So now all I need to do is get a sub, and have no clue what to get. Any opinions?