No they're fine, just make sure you torque up the bolts propperly. Only put them in if your car is already "good". So don't bother if you've got a Corsa if you know what I mean In additon to that, for four points you'll need to use one of the rear belt mounts. Make sure the angle from the mounting point to the angle at which the belt will be under load is no greater than 45 degrees, MOT won't like that.