I would say those are my brackets, but they are not stamped with PNWZR1 and I haven't sold any to Europe.

One thing you may want to take a look at is the metal tangs that fit in the abutment bracket, depending upon the rotor they may rub. Take the tang out and grind on it with a bench grinder some to get some more clearance.

Also check the clearance between the edge of the diameter of the rotor and the tang as well. If it does not fit flush against the abutment bracket, it will hang down and grind on the edge of the rotor.

The pads are likely your problem. You didn't state what kind you're using but try some Hawks and bed them in properly.
Yes, I have C5 brakes and used the bias spring. And I indeed found them to be an improvement over the J55s that came on my '95.

I'm pleased with mt C5 brakes, but I dont break hard from 120 to zero.

I do bring it down from 120 to 35 or so at the track .

I'll probably order new rotors and pads in near future.
I've seen that everybody speaks good about Hawk pads, but what
kind of rotors are recomended?

Also I'll be adding some cooling ducts soon. That should help too.

Rotors arent' going to matter much. Stick with a brand you trust and you'll be fine. Powerslot is a good brand, but they're probably pricey.

You don't need cooling ducts for the street. Add them if you like, but it's only a placebo. You may need them on the track some day, but not for awhile...once you get your brakes functioning correctly you'll be fine.

Problem is that I don't have much choice here in Croatia so I have to order from US. And if I order something that's not good then it really
gets pricey.

As for ducts, I have allready started to convert car for track use since I
really rarely use it on the street. I don't mind driving track car on the
street but vice versa isn't good for me.

Central Coaster, can you explain here, as you did so well on CF one time, about how deposits from crappy and/or improperly bedded pads are generally often much more responsible for the vibrating pedal effect that folks assume are warped rotors? That was an eye-opener for me but I cannot explain it nearly as well as you did.

When you do the ducting, purchase or fabricate a plate that forces the air directly into the center of the rotor and does not just blow air onto it. Otherwise you won't get much effect. You want the air to blow into the center and be dispersed through the rotor vanes, not just blow on the inside surface of the disk.

I am replacing my pads with gm ceramic pads and again with stock rotors.

One of the reasons I converted was that the long term cost of replacing the c4 brakes with the c5's was MUCH cheaper. Plus, the red Z06 calipers look cool; In addition to the beefier C5 caliper and thicker rotors.