does anyone know what the deference is between a 2 and a 4 ohm sub woofer? im getting one tomorow

 

ohms are the resistance of the speaker, if you have one 2 ohm speaker or two 4 ohm speakers it is the same load on the amp, 2 ohms. You need to see how your amp operates, if you have two 2ohm speakers then you can bridge them down to a 1ohm load, this potentially will get the greatest power output from your amp but many amps are unstable at this resistance because so much power will be sent out it will over heat. With that being said you could run into problems with your speakers blowing as well.

What kind of amp are you using?
How many Subs are you getting?
What kind of subs?

If you plan on a one-sub set up then I reccomend a 2ohm speaker it will get more power from the amp because it is less ressistance than the 4 ohm therefore it will be louder, also you shouldn't run into any problems having this type of load on the amp.

If you are going with 2 subs I recommend the 4 ohm speakers and bridging them down to a 2 ohm load.