Upgrade Advise

[Mbjunket]

I'm fairly new to car audio systems and even more so on current brands. I started my first system about 7-8 months ago, started small. I have Kenwwood 6.5" 2 way speakers in all 4 doors and tweeters up high on the doors (about even with the A/C vents). Those are running off the head unit I put in which puts out a meager 40 rms each channel (so it says) but I want to upgrade the mids and highs and an amp feeding them some juice.  I've got an American Bass XFL 10 in a prefab unfortunately. What's odd is I can't find any information about the version of XFL I have. On the magnet it says 1500 rms and 3000 peak, I always see it pictured with 1k / 2k as well as in the specs. I'm using a VFL Stealth 3000.1 amp to push it. I will say I'm pretty amazed on how much bass it produces and no one believes it just 1 10" sub but want a more on the lows and just a little more punch. I think going with a 12" this time is a good decision. At first I thought of going with the American Bass HD 12 but then I started doing some research. The 2 that stood out was the Sundown U series 12" and the DC Level 4 12 m3. Their power handling is on pare with my current amp and they look beastly, plus under $500. Any advise would be great. Been a bass head since I was 12 but I'm finally getting to do my own at 40 lol.