A good "training wheels" way to move toward no-mag is to put the magnet up front. It will help keep the car in the slot and provide some additional traction, but will still allow the car to slide out when taking a corner too fast, with much less of the hard "snap" and deslot you get with magnets in the back. After that, thinner magnet, shimming the magnet, and removing the magnet. This way, you don't feel like you're moving from a car that "works" to one that just spins out constantly.