The subs im talking about are rockford fosgate P3SD410 and P3SD210, both 300 watt rms 600 watt peak shallow mount DVC subwoofers Im asking why would any one buy the 4 Ohm sub when you could get more power out of your amp with the 2 Ohm
Ok in responce to the second answer, is there any difference in quality with these 2 subs??

Why would anyone put more than 100 watts in a frickin car?

it is all in the way you decide to wire them. with a 4ohm dvc you can either get a 2 or 8 ohm load , with the 2 ohm dvc you can get a 1 or four ohm load it all depends on what amplifier you are hooking it up to. if you apply to low of a load to an amplifier it can cause it to overheat and fry it. sometimes you can get more power out of each kind it all depends on what you have to work with without causing damage to it.

How u load an amp determines the amount of power out.

There is a trade off though, the lower the impedance (ohms) the more power is pushed as well as higher distortion & more heat is generated. The excessive heat will shorten the life of the amp.

For best overall performance, it is far better to get a higher powered amp & load it with 4 ohms than a lower powered amp & force it to push more power with a lower impedance (2 or less ohms) load.

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4 ohms subs would make the amp last longer than 2 ohms subs but with 2 ohm subs you can push more power but with 4 ohms subs you can wire them down to 2 ohms.

No noticeable difference in sound quality, although the lower the ohm load on the amp, the greater the heat. TRUE SQ setups have higher ohm loads, but l am talking the one in a million audiophile true, in all honesty, it wont matter Just use whatever load you need to match the watts rms to that of your amp