In the beginning (about 3 years ago)... they where 2 brand new RF Punch HX2 12" - dual 4 ohm. I didn't have my BD1500 at the time I bought these subs. They didn't pull a 2ohm load out of the amp like I wanted. But They were all I could afford at the time.
Then about a year later, one of the coils burnt out on me. So i took it out and ran just a single sub. Then yesterday, a coil burnt out on the other sub. So last night, I put the first blown one back in my car, with the one that pooped out yesterday.
Granted only 1 coil per sub functions now... But it still sounds way better than just one sub.
1500 watts RMS going into 2 coils rated at 500watts max. I wonder how long I can milk this setup. LOL