Peter,
My original Experience with PF pads was not a good one at first either.
I had a 1984 Ferrari 308 GTB the original Brembo’s really sucked I’d tried several different pads none of which really made a significant improvement in fact I remember the PF Carbon/Metallic caused some major vibration with the original rotors (that’s where I’m at with DS 2500’s).
I friend with a Ferrari F355 GTB was boasting how great his new PF brakes where, he had PF pads and new PF rotors fitted and he was right they are incredible. I had the same setup fitted to my car and it the transformed the stopping (even the hand brake worked

).
I never changed the pads again for 2 years (about 8000miles) and that included many ‘ring’ trips plus track days.
I’d like to try the same setup in the Skyline as the brakes have always been an issue with the car.
One major difference though is the Ferrari has the same brakes front a rear so I’d like to try just the front rotors first then the rears.
Paul.