Kicker comps are SVC I believe
here goes, these are just estimates, they may be off:
(3) 4-ohms in parallel would be around 1.67 ohms
(3) 4-ohms in series would be around 12 ohms (not 100% sure about that though)
(3) 8-ohms in parallel would be around 2.67 ohms
(3) 8-ohms in series would be around 18-20 ohms (not 100% sure)
going in series is not always the best idea, as your load decreases so will the power your amplifier puts out. So if an amp is rated 600 watts @ 4 ohms, then it will be around 300 watts @ 8 ohms, maybe less.