engine cuts out under light load at 4000rpm

After a new catback install the car (holden monaro) cuts out at 4000rpm just accelerating, it jerks violently going dead like a hardcut limiter at 4000rpm. Doesn't throw any error codes although it did come in with a crank angle sensor code among others that have been cleared. Only started playing up approx 100kms after the cat back exhaust install. it is not a mechanical cut out it is complete loss of spark or fuel

ideas would be great.... if not it will be onto the dyno and start searching

Car is running maffless 2 bar tune with magnacharger supercharger, long tube headers, 4 bolt 90mm dbw gm throttle body

Have the tune and any log files on this happening?

Didn't get a chance spent most of the day on a customers race car and didn't get to mine, had a quick look and it has some over voltage coming in from the alternator so will get that sorted before i go any further, could be the problem or fried something as a result