The carpenter engine is a race engine, and works by freeing up the intake and exhaust (including the head ports) to allow more air through (more air = more horses), and also shifting the power delivery characteristics up in the rev range with cams and other stuff to facilitate higher rev limit... because torque and hp are always equal at 5252rpm, the more torque you make higher up in the revs the more horsepower you will make.
And the more revs you have the more power you will make, because more revs means more air means more horses... provided it is cammed to suit and the engine can breathe i.e.. intake and exhaust suitable.
The peak torque of the stock bike and the Carpenter bike will be similar enough but the real difference is their cams shift that torque band way up the revs so the engine makes way more power.
Basically you have to wind the Carpenter engine up in the revs to hit its 'powerband', whereas with the stock bike its powerband is pretty much from idle.
The Carpenter bike is a lot faster than stock bike but you need to rev them out. Like if I do a roll on in top gear on my Rocket from 50mph vs my hayabusa in top at 50, the rocket embarrasses the busa.... but drop a few gears so the busa is in its powerband I.e. up in the revs, it will destroy the Rocket after 70 or 80mph.