996.1 C2 help

[Richie200]

I slightly damaged one of the white cables on removal of a Lambda sensor(as seen in picture, only 1 or 2 strand cut though); would this have any effect on the engine power if the DME is receiving an error message from the Lambda/O2 sensor? Also if there was a less than perfect Lambda sensor reading, would this give an indication (engine check light)?
Reason being I fitted new 200cell cats today but didn't really notice any performance gain, if anything the car is running less responsive. I was expecting a noticeable mid-range gain and the typical 3000rpm flatspot to be no more???