There was a thread on rear hatch lifts a while back. Someone was looking for stronger lifts and they came up with a couple of part #'s at McMaster-Carr. If my memory is correct, the factory latch lifts are 175psi. The person found 225psi and 200psi lifts, the latter I purchased for my 2006 LE. The lifts actually increase the hatch door height about an inch when opened and the door pretty much lifts itself once you get it slightly open. I remember there was a change, I think, in 2010 or 2011 regarding the thread size of the one end where the ball end screws onto. You might try searching the forum for the thread; it was pretty long, like around 12 or 13 pages, if I remember right.
The 200psi ones I purchased for my 2006 Pathfinder were #
9416K148. They're $19.26 each plus shipping:
http://www.mcmaster.com/#