2 vs 4 ohm subwoofers

hello experts ,

I have an altima 2005 and I have already  replaced the four OEM speakers with Alpine's R-Type speakers

in the front : SPR-17LS

in the back : SPR-69LP

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now im planning to intall a 12''  R-type subwoofer with

this amplifier : MRD-M605

to acheive the best configuration without affecting the car electrcity or the car head unit or draining the battery or over heating the amplifier

should I go with this subwoofer

SWR-1242D(4Ù + 4Ù)

or

SWR-1222D (2Ù + 2Ù)

they are the same in everything except the ohms

and thanks very very much who would give me a little help

this is the specs of the amp

http://www.alpine.com.au/products/product4.asp?id=211

and these specs of the subwoofers :

http://www.alpine.com.au/products/product4.asp?id=221

http://www.alpine.com.au/products/product4.asp?id=222

I have olready replaced the OEM car speakers

all the matters now is chosen correct subwoofer with that amp

thanks

as it's written in the website in the diagram

the amp will go fine with both subwoofers

but i don't know what is the difference between them ?

any recommandation please?

so which subwoofer should I buy ? the SWR-1222D (2 ohm ) ?

or the SWR-1242D (4 ohm) ?

yes now i got it

so I will buy the SWR-1242D and wire it in parallel .

thank you very much guys