Here is a compare of 2 C6 Z06s, one stock that PCM auto opens and closes the damper in mufflers and another with the fuse for damper pulled
As seen the lower graph of the Z06 with fuse pulled is the fuel trims ( LTFTS) greatly imbalanced to each other.
This is due to no backpressure and not allowing both heads to move the exhaust at the same volume