Just Finished my rear seat flat plate. Also used it to remount the battery here instead of the the trunk.
First the weights out of the way
The CF plate 2.25lbs + the black carpet covers 1lb =3.25
-minus old carpeted rear seat delete + stock center carpet = 2.5lb
Ill add in .25lbs for bolts so total gain is 1lb
I could shorten the power cable a bit and lose some weight but I left it alone for now
CF Plate

Carpeted pieces - pet slept on adding hair weight haha

-old Carpet pieces + stock piece
NOW ONTO The PICS!

Carpeted piece. Used Rivnuts into the stock side armrests for mounting.

Seat installed

Used 2 small braces under the plate, plate is riveted to brace as you can see under battery