I have a Kenwood amp that is 2-ohm 300w RMS and at 4-ohm 500w RMS and is 1000w max power. I want a Kicker L7 but i don't know if I should buy the 2-ohm or 4-ohm version. Which one should i get?

 

Are you sure you're reading it right? What is the model #/name of the amp? Usually, if the amp has different power ratings at different impediance loads, the lower the impediance, the higher the power it puts out. I don't see how you get more power running 4-Ohm versus 2.. After that's all figured out, it should be a bit easier to choose a driver.

 

My bad i read it backwards it is 500w at 2-Ohm and 300w at 4-Ohm

 

Okay. Since you only have 500WRMS on tap, I'd stay with one 8" L7 (4-Ohm).
I'm only recommending this because I'm not sure what your plans are as far as any possible amplifier/subwoofer upgrades. (Subs also sound better a bit overpowered than they do way underpowered) But since you're looking to get an L7 and power it off of the above mentioned amp, Get an 8" 4-Ohm, wire it in parallel to present a 2-Ohm load to your amp so you'll get the 500W instead of the 300. Give it a 1 Cu.ft. box tuned to ~35Hz and it will bump. More than you probably think..