This sure is getting confusing!A bass blocker is simply a capacitor that acts as a filter. Some of the more expensive units use a coil as well to increase the rate of cutoff. The rating on the capacitor in conjunction with the impedance of the speaker determines the bass cutoff frequency.
In order to do it correctly, we need someone to verify the speaker impedance on the Kickers 4ohm or 2ohm? And then I can size the capacitor or you can just buy one that's set for 250-300 at the speaker impedance.