Each voice coil is 4 ohms.

If you wire those in parallel, it goes down to 2 ohms.
If you wire those in series, it goes up to 8 ohms.

Since you have 2 subs, you can wire it a couple different ways.

I think the best way to wire it would be to go for a 4 ohm load.

To get that you wire each of your subs to an 8 ohm load, then wire them in parallel together to get a 4 ohm load.

See this diagram.



You will be under powering them by a bit, but it is the best you will get with that setup.