I tend to run whatever psi gives me even wear across the surface of the tire. 34psi for a while now, and doing fine. My crappy OEM Bridgestones are wearing evenly (and quickly). Those Grabber HTS shoes are on daddy's short list. That said, if performance is the immediate issue, it's a matter of trying to help get the car "neutral" -- avoiding understeer or oversteer due to inflation given the way the rest of the car comes from the factory.What tire pressure are you running and why? In my 07 SF GLS I'm running 35psi as I feel it handles best, could be the placebo effect?
Are those pressures on the stock tires? I went up to just 32 all around and the ride was unbearable with the stock tires.35 front, 32 rear. You can check for even wear by drawing chalk lines across the tread, driving a little and see how the wear patter is.
DON'T forget the Spare! My limp along was down to 28# !