im guessen you mean heavy breaken,,,in the sense that when a light turns yellow and you floor it thinking you can get it, but then it is not possible and you realize it, so you slam your brakes to come to a stop at the white line....well in that case, my car does the exact same thing, and I have stock wheels, alignment and everything. i got khumo's on but it was doing it even with stock tires....though the only time it happens is around interesections and stuff, because here in jersey we have grooves that run parallel to the direction of traffic. these aren't small grooves, they are like 2 lumps in each lane running parallel to traffic, and during breaken if either side of the car tires, catch a groove it kinda pulls it a lil to the side, sometimes to the left and sometimes to the right...this is the only time that i have noticed this happeneing...good luck and let us know
peace!