I've just got the new one installed on my AT4. 4" Bose factory sub doesn't do it for me, so I ordered this one and had it installed in a shop. Took guys about 1.5 hour - not super easy.
It looks well made, guys said it's a 10". $600 online with shipping.
This sub comes with an amp mounted on a side. Amp looks bare, but if you unscrew it there are adjustment switches on the bottom and one plug next to harness. Kicker support says I can connect this knob there to adjust level: https://www.kicker.com/CXARC-Remote-Control-for-Kicker-46CX-Series-Amps
Initially I hated the thing - it was so obnoxiously strong that I started to worry that paint will peal off the cab. Adjusting bass in the head unit EQ helps somewhat, but still not enough and affects sound in a bad way. Wrote email to Kicker and they told me how to adjust gain with those switches - this info is not present in the manual, for whatever reason. Switches 1,2,3 control it. No idea what other switches do and I wouldn't touch them. They also said that I can use that knob for fine tuning, so I'll also install it on Sunday and see how it works. Anyway now after changing gain with those switches it's a completely different thing - sounds really good, deep and not annoying, makes huge difference in all kinds of music. Love this thing!