How big of a sub amp do i need?

You will be good with any mono block amp that puts out 1000 to 1500 watts RMS. And the v3 just stands for the version it is. And the other number after that is the ohm rating.

You will be good with any mono block amp that puts out 1000 to 1500 watts RMS. And the v3 just stands for the version it is. And the other number after that is the ohm rating.

Although it may be out of your price point, I would definetly recommend either the JL 1000/1 or the JL HD1200/1. The main reason for suggesting those amps is not only because either amp will provide the power you need, but are also very good quality amps, to compliment the subs you are purchasing. Each 13w3 handles up to 600watts RMS power, so you should get an amp with enough power to push both to their potential. Now, there is different versions of the w3, hence the 'V', but there is no version 4. I can only assume you viewed a w3v3-2 and a w3v3-4... the trailing number referring to the impedance of the voice coils. Now, getting a 2ohm sub vs a 4ohm sub makes a big difference when it comes to choosing the right amp to power them, but with the JL amps, they push the same amount of power, regardless of impedance (ohms rating), thanks to their regulated intelligent power supply, or R.I.P.S technology. Sure, you could find an amp for much less money that will push the same 1000 watts RMS, if not more, but in my opinion, if you are going to run nice SQ subs like 13w3s, get a nice quality amp to compliment them. To be honest though, I paid more than your budgeted amount on my 1000/1v2, and I bought mine used. That being said, its the last monoblock amp I will ever buy. Hope this helps.