If the font end is real low. It may be contacting the lower control arm snubbers on decell. Or it has drastic toe change thru the range of travel. Mine has followed seems in the pavement when it had toe out. But it's never shook, even at 148-150. How are the shocks? Ever see a car run down the freeway with a wheel hopping up and down? Wonder why the driver doesn't feel something? Lack of shock control can produce some weird harmonics.
Doug