Ok I talked to someone at Autopartswarehouse.com
They say that the EBC dempled and slotted rotors will fit the 05-06 GTO.
Here are the part numbers and prices.
Front:
#E35GD7298 $231.95 (Free shipping and handling)
Rear:
#E35GD7300 #201.95 (Free shipping and handling)
Here's the link to the website:
http://replacement.autopartswarehous...20Disc&dp=true
Mate these with some Green Stuff or Red Stuff break pads and I bet breaking is improved 100%.