Looking for some advice.

I just recently sold my 2 Kicker L3 12's and am looking to get a different subwoofer setup. I've considered maybe doing one Rockford T1 or something of the sorts. I'm open to any suggestions that anyone might have though. I'm looking for something that will still give me good deep bass, but better clarity than the Kickers and also something that will leave me some space in my hatch. I've already upgraded all of my door speakers and tweeters and have a Rockford Prime series 1000 watt amp, so just really looking for the subwoofer. I am open to getting a new amp if needed though,and I have a budget of around $400 to work with. Thanks,

Andy