Those calipers are cooked. Brembo's powder coating will darken with excessive heat. Check your dust boots, they are probably fried and I would not have high confidence on the piston seals. Time for a rebuild. This discoloration was a little more common on the Gen5s, especially SS 1LE's that did not have any brake cooling. Ever wonder why the Gen5 ZL1 had black calipers form the factory?
lol. That car had cooling but it was 580 HP and heavy!
Do yo have the brake deflectors installed on the radius rod (forward, angular control rod)? They came with the car, installed. Regular SS's had much larger flat ones in the trunk at delivery, and until recently those were the ticket to improve front brake cooling. But now the CT5 BlackWing front deflectors are the go-to for improving cooling.
But realistically you are using a much more aggressive pad and the car was not engineered to use that pad. But even at that, there's plenty of guys using those pads and don't have issues. At your skill level you shouldn't be overusing them. The mode selection can matter but usually it's the rear brakes that see the most use to settle the car. If you have good car control, Race mode will be a breeze. I typically run "all off" at my local track, Pitt Race.
Since your pedal returned, it was not fluid boiling. SRF has hot compressibility. I experienced it with my Gen5 SS 1LE. Once the fluid cools down enough the firm pedal returns. Brembo HTC64T and Endless are better for that trait. I wouldn't think you faded those Hawks.
I ran the Alcon caliper stickers on my 6 piston front Gen5 ZL1 equipped '14 SS 1LE. And I ran Raybestos ST43 race pads. Lots of heat. Even though I had lots of cooling, my calipers saw 450*F. I currently have a BCD (copper free package) equipped '22 SS 1LE. The most aggressive pad I've run is the Ferodo DS1.11. Since the BCD brakes are thermal overkill on an SS 1LE the most caliper temp I've seen is 250*F (below pic).
