Supercharger boost with floored pedal missing

Hi all

After my 1995 XJR / US version had noticeable slowed down and started making noises, my mechanic found the supercharger (Eaton M90) to be the culprit and I got it replaced with a used one.

Car is clearly faster again, but I miss the very noticeable acceleration boost (you could hear it too) when the gas pedal is fully floored. Which was always very helpful during overtaking. For example, the car needed only 6.5sec from 0 to 100kmh.

This is now missing. What could it be?

The throttle is a little harder to set properly on the TRACTION CONTROL cars.
Check to see if the throttle is opening all the way when the pedal is on the floor.
Check physically and look at the TPS signal in the ECM data.

Thank you!
Will tell mechanic to check that, and report back here for update.

My suggestion would be as per motorcar man. Check the calibration/settings of the throttle body. Can make a huge difference.
Did the replacement supercharger come with the same size pulley as your original one? Because if it did not, that could be the problem too. A larger pulley will get you less air. The standard drive belt can take up a bit of difference in pulley diameter. But the telltale is the wear indicator on the tensioner. If that is way off, you might have a different pulley, or a very worn belt, of course.

Good luck