the 26 psi information was superseded as it was found to be too low, think it went back up to 30.
there has been quite a lot written on this, (chalk test thread). It seems that it can vary according to what model, what tyres and what type of driving.
I did a bit of trial and error on mine (td4 auto) and found the best handling / tyre wear to be at 34 psi, but mine is a commercial with sh*tloads of gear in the back, and does a lot of motorway miles.
I'd be inclined to start at 33 and work your way down, try letting out a little each day until you find a pressure you're happy with.
good luck