I replaced the middle row seats with a combination of Trakkers/Exmoor
Trim Hi/Lo Back seats, and must admit to being a tad disappointed.

They were much better for the kids than the standard fare, more
comfortable and safer, but still small for adults, and the seat backs
were still very upright. Fine when the kids were awake, but left them
hanging off the seat belts when they fell asleep.

I also bought and fitted the seat extensions from Trakkers that gave a
couple of inches more leg room - although this worked and was a big
improvement it achieved this by moving the seat back upwards and
backwards, resulting in a large hole at the back of the seat - just
right for losing all sorts into the rear load bay. For what you get, a
few metal brackets and a handful of bolts and stuff, I thought it was an
expensive modification, especially as I had to drill holes in the seat
frames to mount them.

I believe you can also only use the extensions if you have the four
individual seats in the rear, and not the six seating benches.

Mark