A fox with coilovers doesnt mean shit. Springs dont make a car handle that much better unless the previous springs were just totally wrong. The only impact they would have would be on the balance of the vehicle and lowering the center of gravity. How the suspension is setup and what type is what makes all the difference. That being said there are fox mustangs out there that are more than capable of dusting that Z06. Hell, in hot rod magazine a couple years back they had a 64 GTO that was built to spank porsches and ferraris and thats exactly what it did. Bigger body muscle cars arent exactly known for their handling. Heres the article. 1964 Pontiac GTO - Never Give Up - Featured Vehicle - Hot Rod Magazine