Correct AFR with a Predator??

I need to know the optimum AFR for a 2004 Cobra with a Predator tune? I was told by a TUNER that to keep from burning up my CATS that he needs to set the AFR at 10.5? Isn't that too RICH? I'll be running a Magnaflow "X" pipe, Magnaflow CAT back, Steeda intake and a Predator tune. What are you guys seeing for Air Fuel Ratios from other Tuners?

Thanks
GLWBEAR
2004 Cobra