If you're planning on running a 13.99 or quicker e.t., you'd better have a driveshaft loop, unless you're running street tires. If you're running street tires, 13 or slower e.t.'s are exempt. We plan to add slicks, so we contacted Summit Racing for our loop. The loop must be made of 11/44-inch-thick and 2-inch-wide steel and must be within 6 inches of the front universal joint. The loop must be mounted to the frame or steel structure of the car. In our case, the steel structure is the floor.