What would sound louder? One 12" kicker cvx that's 750 watts rms or two 12" kicker cvr's that are 400 watts rms each?

 

Doubled cone area or power = +3dB from the starting efficiency.

Lower frequencies are louder to the ear, so "sounds louder" is frequency/box dependant. With the same tune, generally the setup with more cone area will be louder on lower frequencies.

Both in the right ported box tuned between 30-40hz will be loud enough for daily. While a high-tuned 12" (40hz) will be loud, you might want better lows, so what are you listening to?

CVX 12 sensitivity 87.1 dB
Frequency response 20-500 HZ

CVR 12 sensitivity 86.9 dB
Frequency response 25-500 HZ

Two 12's will have better lows, but do you have the space for a ported box (3.5-4.5 cubic feet)?

There are better subs than the CVR and CVX for the same (or less) price.

 

What other subs would you recommend for the same price or cheaper that are better? And I have a Cavalier for a vehicle and I want to put it in my trunk.

 

Look at Fi car audio, there are a whole wack of unpopular brands that are way better than Kicker.

 

I would say the 2 CVR's.

 

If your choice is between 2 CVR and CVX, go with 2 CVR's. Look at the Fi SSD.

 

Neither will be loud without a proper amplifier and electrical