Had a ‘16 Ellison that came with a Sony system. OEM sub installation was in the furthest rear driver side corner. It was not very good; in performance that is.
Ended up removing the speaker enclosure and ditching that horrible speaker. Replaced with a Kicker 8in. Had to make minor modifications to the enclosure, as the speaker mounting did not line up.
Filled the enclosure with poly-fill to trick the speaker into thinking it was in a larger volume enclosure.
Additionally, because the speaker out-spec’d the OEM model so much I also added an amp. Mounted it under the driver side third row seat. FYI: spaced the seat bolster brackets to gain clearance for an unobstructed power fold.
Could I have mounted a larger speaker and amp yes; kinda wanted to. But, wanted something that didn’t take up space, obstruct the way the truck was used, and be totally out of sight.
If you can find that JL enclosure in the advertisement it will allow you to mount a 10in sub in the stock location. Mind you, you’d need to find your model year equivalent.
Once I came across that it was a no-brainer. But, I could NEVER find one. Anywhere!!! Good luck on whatever you decide to do.
P.S.- the other thing I added (might be getting the name wrong) was a digital converter. Gotta take the DSP signals the vehicle produces and turn them into usable signals for the amplifier. Don’t remember the brand, but I mounted it in underneath middle row cup holder. If any adjustments needed to be made all I had to do was pop the cup holder out. Don’t have a pic of that mounted; or, I can’t find it. Sorry.