ZL1 brake ducts arent really brake ducts. They just push more air into the wheel well not neccesarily on the brakes.
The fluid shouldnt come out of the bleeder valve, make sure its closed and that you arent overfilling the resevoir.
Stainless lines help, better pads help, better rotors help, heck even better calipers help.
I run racingbrake products and have been on a course while it was 117 degrees with no brake fade. Might want to try their products. They reduce weight, heat, and brake better.
Mr. Pete gives sound advice with a complete fluid flush. I would go further and recommend a tech II bleed/flush at your trusted dealer.