Which begs the quesion : how was the extra torque made ?
I would say by little tweaks to the ignition, fuel & boost maps to improve torque plus wasted spark systems can give better control of igntion spark which allows a more otpimium advance for torque, but the catylst been an early generation type will act as a restrictor on the exhaust that can affect torque output as it gives the turbo something to work against which flatterns the torque curve as the gases cannot get out as quickly.
Fair one.