This is for my own vehicle. I do not work in the 12V industry.
A little bit about my current system:
Front stage is Mid and Midbass drivers from the Focal KRX3 3-way set in factory locations, and Arc Audio Black Series 1.0 tweeters.
Rear is OEM 3 inch mids, used for rear fill
Processor was car PC, just replaced with Alpine PXA-H800 (car PC was too much of a PITA)
Subwoofer is a Boston Acoustics SPG-555 in a sealed box. The box is bolted against the backseat, firing directly through the ski hole.
Car is a Bentley CGT. This has been my car audio hobby car, and it is not a daily driver (about 50% of the time) I am not afraid of cutting panels, etc.
Here is my dilemma. I saw the Elite.4 on display at a car audio shop I go to from time to time. It was not powered or anything, but I was intrigued by its design, and I took a flashlight to it and looked through the cover. I think blood pressure in my brain dropped

I ended up ordering one Elite.4 and one Elite.1.
Upgrading the alternator on this car is probably not an option, but I can easily add some power cells if needed. I do not plan on using all of the power the amplifiers can put out, but who cares. It's nice to have the headroom anyway.
I am however a bass-head and I would like to use the Elite.1's output capability to the fullest, especially since it is so efficient due to being a class D design.
Initially, I thought that I could order a couple of the PG Elite.12d subs, but I hear that these are not available anymore until they are re-designed, because the Elite.1 amps are frying them. Is this true?
In any case, I was not able to order Elite.12d subwoofers. My plan was a sealed box, firing through the ski hole.
Can someone recommend a pair or subwoofers that would be suited for this amplifier? A sealed box is easiest for me to build.
I believe I can fit a couple of 15s also.
If someone has the tools to help me model a box that would use a slotted port through the ski hole, that would be best

Also, I am open to replacing the front stage, if anyone here has any ideas. I dont mind using obscure brands, DIY drivers, pro audio drivers, etc.