wiring them in series increase ohms
in parallel decreases ohms, increases current.
Resistance in series = R1 + R2 + ...
in parallel = 1/R = 1/R1 + 1/R2 +...
if you are wiring that many subs/speakers, try and get a 1ohm stable amp so you can wire more stuff in parallel and hope to not kill anything that cant handle the extra current.