Sony Wiring Issue

Okay, my buddy has a single channel Sony XM-D1000P5 amp. He also has two Sony 10s with single 4 ohm voice coils.

The odd part is that his mono amp has TWO speaker outs. Currently he has each of his two tens wired to each speaker output. The subs hit hard and sound good how they are running now. But we having been thinking that if we wired it the subs in parallel, pushing the amp to 2 ohms, then he'd get a little more power out of the Sony amp.

So, he's gotten rid of the amp's manual and we are trying to figure out what is the best option for this system. After some research, he believes that the amp is not bridgeable, which makes sense as it is a single channel amp. If he wants to wire this amp to a 2 ohm load, which speaker outputs does he use, or does he 'bridge' the two speaker outs?

As you can see in this picture the tw speaker outputs are the right four connections at the bottom of the amp.

What he wants: 2 ohm load on amp, parallel wiring connected to 2 4 ohm subs. Any help would be awesome.

Thanks guys

Thanks man, thats what we were thinking.