I am running two 15 spl soundstream woofers with a
the 15 spl woofers are dual voice coil, i believe 2 ohms per voice coil.
the 500sx amp is rated 4 ohms bridged at 500 watts, it is capible of dropping to 2 ohms sterao, but no lower than 4 ohms bridged. to get maximum performance, you cannot use both voice coils of both speakers, you can only use one speaker, or both speakers, while only using one voice coil from each.
there is no point of bridging them, you can achieve maximum performance by attaching one voice coil from each speaker to each channel of the amp, while leaving one voice coil from each speaker unconnected. you could also use just one speaker, attaching one vioce coil to one channel, and the other vioce coil to the other channel. then, i would suggest getting a second, identical amp to run the second speaker.
if you are persistent on bridging to mono, then you can only use 2 voice coils (both from one speaker, or one from each speaker) and you must run the voice coils in series, that is, from the amp positive to the 1st vioce coil positive, then run a jumper wire form the 1st vioce coil negative to the 2nd vioce coil positive, then, finally, run the 2nd vioce coil negative back to the negative of the amp.
this is all assumming that each voice coil is 2 ohms and each vioce coil has seperate inputs, meaning that each speaker has 2 pairs of speaker terminals.