Series/parallel/series should get 2ohm.Series 2 coils to 2 ohm do the same for the other 2 coils(same sub) then repeat the same thing for the other sub.Now connect the 2 2ohm leads on the subs in parrellel to get 1 ohm(do the same for the other sub).Now connect the 2 subs together in series and you should get 2 ohms.