I've built 2 160+ daily/demo vehicles with AQ subs. My daily beater trunk car is a single HDC4 18 off 2 3500's that does a 54.9 in the kick and gets pounded on daily since it was built to play music, not burp.
I've reconed AQ/DD subs with other brand recones, some gained a lilttle, some didn't, most of them smoked also. Of course I have guys on my team that blow up EVERY brand out there.
Will you have 4kw clamped or a 4kw amp? BIG difference...
Get an HDC4 18 while they're still on sale, problem solved.