I was thinking performance foam (makes it more comfy)
Seat slide (recommended for users over 5ft 10 and im 5ft 11 already and growing)
And a headrest.
This will be expensive but its for my bad back and all the other chairs we have had are crap to say the least.
Imo arm rests (can be added at a later date) may get in the way etc. and the extra lumber support can be replaced with a cushion or somethin if necessary. What do u think?