i used the old 4 spoke quad 1 ohm 15's and the new style quad 1 15's and they blast good. I ran two 2500d's to each and the new ones were a bit louder but the old ones would never die. Bob Perillo on 420 is where I got all of them from, and he even said in his walls the old 4 spokes never lost coils just lost cones unfortunately they only got so loud and stopped no matter how much power you fed them, but the new style would blow easier yet get louder....
I loved mine, but i'm sure there are louder subs out there