Have you driven with a pedal box before?
If not then that may be all it is! They take a lot of getting used to having no servo assistance makes the pedal very hard and if you want to stop then you have gotta mean it lol
if it is specced correctly then the pedal pressure and feel is so much better than a servo system.
I have never had to stamp hard on any of my pedal boxes to make the car stand on its knees.