didnt find the table of down forces, but heres an article talking about them
No Spoilers: @ 115mph 375 lbs of lift in front, 25 lbs of downforce in rear.
No Spoilers: @ 85mph 200 lbs of lift in front, 10 lbs of downforce in rear.
Front & Rear Spoiler: @ 115mph 330lbs of lift in front, 130#'s downforce in rear.
Front & Rear Spoiler: @ 85mph 175lbs of lift in front, 75lbs of downforce in rear.
Rear Only: @ 115mph 450 lbs of Lift in front, 150 lbs downforce in rear.
Rear Only: @ 85mph 250 lbs of lift in front, 95 lbs of downforce in rear.
Front Only: @115mph 275 lbs of lift in front, 20 lbs of downforce in rear.
Front Only: @ 85mph 120 lbs of lift in front, 10 lbs of downforce in rear
Additional info on the RPO_D80 option
http://www.camaro-untoldsecrets.com/articles/rpo_d80.htm