It's not the plastic behind the armrest you have to worry about - it's the solid metal seat backrest that really needs cut.
There are (2) P/N's for metal seat backrest: (1) with passthru, (1) without. The difference is the one already has the proper size hole for the pass thru punched out of the metal.
Yeah, you could just cut a hole in yours in the right place, but when I looked into it, the carpeted panels that cover the rear of the seats (at least if you have the fold down seats) are friggen glued on and while attempting to remove one it definitely looked as if removing it would ruin it.
If it wasn't for this fact, retrofit would not be bad, cut a hole in metal, install the passthru plastic framework parts & ski cassette.
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