I Know this should be in car audio section but i need to know rite now...

ok i have Pioneer DEH-74000 mp3 deck....and a rockford fosgate 360 amp....

i want one subwoofer...

my friend is at store rite now waiting to buy my subwoofer....

they have Rockford Fosgate HX2 dual 2 ohms, and Rockford Fosgate HX2 dual 4 ohms....which shold he get for me...

keep in mind i'm only gonna have one sub....