Porsche recommends 2.0 bar front, 2.5 bar rear (29 and 36 psi)
I use this pressure.
My tires are 225/40 ZR18 and 265/35 ZR18 (pzero rosso)
Well, the rear tyres are worn away just in center side, so it could be a overpressure.
I would like to make a poll to know which pressures you use in your boxster 986!
Just collaborate! all of you!
Best regards.