you are describing midbass. effectivly ~125hz is where most of those 'kick' frequencies lie. your best bet is to upgrade your midwoofer\midbass to something that will play those frequencies with authority. there arent many optimal drivers for this application in cars today (for my tastes of midbas that is)
eaither they are 8ohm, or like 6" mounting depth, or like $200 each, they are just hard to find in general.
you are looking for a speaker that plays from 50hz~3000hz +\-3db, preferably 2ohm (for more power+cheaper amp), very shallow mounting depth so you can fit them in doors and kicks easy, and between 6.5 and 8 inches.
there are a few that come to mind;
the IDQ8 - problem is they are too rare, and they do have like 4~5" mounting depth - ive seen mint DVC4 pairs go for ~$500 on
ebay.
Illusion Audio ND8i - again, simply too hard to find. front mounted neo motor for a 2.5" mounting delpth, dvc4 plays up to 3khz, great speaker, but it will cost you IF you can find them.
planet audio P8NEO - practically a clone of the illusion driver, again, not made anymore and hard to find. prolly cheaper tho.
critical mass MB82 - these are for sale on the critical mass site (listed as an LS82 - i was told that this is a typo) they are like $250 EACH tho. so you pay a preimium. similar to the illusion driver, but tweaked alot and they are supposed to be real nice. *this is what i plan on getting soon*
there are some seas drivers out there, some dayton drivers, some vifa drivers, all of these have pretty large mounting depths (4~6") and some of them are 8ohm - not to mention $150 per driver.
if you can afford $5~600 for a midbass driver, i highly recommend the critical mass (you can order them from the site, but again, it will cost a pretty penny). but i do not claim to have expierence with them. i talked to the tech guy wade for like 2 hours a few days ago and he told me everything i was hoping to hear.
also if you cant afford and cant fit midbass drivers, try a sealed box with a higher lowpass. i know my IDQ12's crossed at 90hz in an infinite baffle had some SERIOUS kick to them. i loved it. but i also had sealed glassed doorpods for some image dynamics CX62 midbass drivers playing from 90hz to 1.5khz, so im sure that helped lol //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif