Are you trying to get a smoother, but still efficient ride?
The usual method is to put 10 psi less pressure in the front than the back (with both tires the same size). With the 25c in the back and 23c in front, use about the same lower pressure in both.
At 170 lbs, I use 90-95 front, 105-110 rear in 23c. And 85-90 front, 100-105 rear in 25c, and could probably lower the front to 80.
A lightweight rider could start with 85 in the front 23c, and 95 in the rear 25c.
I started using GP4000 25c tires last year. They are still fast, but better on the rough roads than the same tires in 23c.