New Kicker Cvr 10's Not T...?

2 new Cvr 10's in a sealed box. Power Akoustic LT-980/2 pushing subs. Alpine hu with sub output. The amp xover is set on Low-F around 80hz. My problem is that there is barely any thump to them. However, when I set the xover on the amp to Full-F, they thump but more of a mid-range thump. I have tried to tune the amp with Low-F setting, but nothing. Amp does have a b eq, and subsonic filter but no thump. Amp pushed 2 12's before. Speakers were in box already. Capable of 2 or 4-ohm. Am I missing something?????