you can most likely bridge your amp @ 4ohms, or run each channel @2 or @4.
these subs are 4ohm. you can run one sub off each channel and itl get like 200w most likely, or double up- wire down to 2 ohm, and they will still get 200ish watts.
the 'rule of thumb' is usually this- whenever you step down the resistance, your power increases, but alot of amps are not stable with less resistance. most amps can NOT be bridged lower than 4ohms, and can not be ran under 2ohms in any circumstances. there are many amps that can do this- but as a rule of thumb, dont bridge lower than 4ohms, or run lower than 2ohms (seperate channel) unless the manual says so - or you know otherwise.
so its eaither two subs, seperate channels - ~200watts, or 4subs, 2channels, ~200w each.
id go with 4. much louder.