People always repeat this myth with nothing to back it up. Look up the Plaid's actual braking numbers compared to any other high end sedan. It matches or beats them on stopping distances. The track pack isn't going to dramatically improve that. You're at the limits of traction. Where the track pack will help is repeated stops / fade resistance (i.e what you would expect on the track).Any idea on if the brakes on M3P are appropriate for the car? On the Plaid you really need the track package if you want the braking and acceleration balanced. The yoke is cool but I never got as good with it as a round steering wheel for spirited driving.
Ultimately if you want a car that can stop drastically faster than it can accelerate, you're going to need something with less than 1k HP.