It is like the Pedal Commander. Many people claim through videos and reviews that it has a big improvement on throttle response.
For all the "snake oil, prove it" folks, 1) Murder After Midnight isn't selling anything, he is a customer.
2) it WILL increase acceleration more than just mashing the Pedal.
I'll explain "2)"as simply as possible.
ALL fly by wire pedals have a delay, lag...in the beginning of pressing the throttle. Some more than others.
The Pedalmax and Pedal Commander and the like, simply increase the output signal. So where you had a delay or lag in the beginning, it is now getting a stronger signal from the lightest touch. That increased signal continues through the entire range of the Pedal. With them you can dial it down for fuel efficiency or up to very aggressive, where the lightest touch of the Pedal will be like mashing the gas and it will increase with that higher input through the whole range of the Pedal.
That said, it should throw you into your seat harder if set aggressively and since it gets a high input quicker, should shave a hair off 0-60, but only a hair.