buying a new sub.

In my firebird, i have 2 stock 6.5in subs that came with my monsoon system. whenever the subs hit a low note when i listen to rap, they sound like they are bottoming out. so im looking to replace those subs. i found some Rockford Fosgate HE RFP4406 6.5 subs and Elemental Design subs. the RockFord's say they respond to 42-800Hz. the Elemental Designs repond to 20-1000Hz. Would it be better to get the Elemental Design subs?

Elemental Design:
http://edesignaudio.com/product.php?cid=15&pid=32&tab=Specs&cur=USD

RockFords:
http://www.epinions.com/pr-Car_Speakers_Rockford_Fosgate_Punch_HE_RFP_4406_Ca r_Subwoofer_Driver_RFP4406/display_~full_specs

Hell, I'd go with the Elemental Design. Human hearing is 20-20,000 HZ. I'm sure your speakers can do up to 20,000 HZ. You'd like your lows to go all the way down to 20 HZ, right? Then that'd be the way to go.

yeah, thats what i was thinking. anybody else got any advice?

EDs

Hell, I'd go with the Elemental Design. Human hearing is 20-20,000 HZ. I'm sure your speakers can do up to 20,000 HZ. You'd like your lows to go all the way down to 20 HZ, right? Then that'd be the way to go.

this is why I prefer sealed boxes