If you have two 4 ohm SVC subs, they can be wired at 2 ohms or 8 ohms on a single channel. 2 ohms will get you the most power as long as the amp is stable at 2 ohms.
It depends on the amp most are not 2 ohm stable bridged but a few are check your specs. if not one sub per channel would work well too. What amp do you have?