Hate to say it but 03 cobras are slow for the power. I had one and even with 600 plus at the wheels it was a joke compared to a cam only c6z06 and than the ported heads, intake and 200 shot came. Even without the nitrous the car is in a different league. Same applies to gt500's other than the 13.
Probably the most accurate thing I've ever read on the internets.