Here you can see exactly how the fuel rails will fit in the valley pan and where the fuel pressure regulator is housed. The parallel rails will be plumbed together with a T-fitting from the fuel feed line. The regulator will be plumbed in at the opposite end to control fuel pressure at the return line. This system, typical of fuel injection, creates pressure on the injector by controlling backpressure, which forces fuel into-instead of past-the injectors. According to technical sources such as Kinsler, this type of parallel plumbing provides increased fuel capacity and reduced fuel velocity in the rails, and provides better fuel distribution. According to Troy, the hardline plumbing lines will hold the rails in place, although HHR will reinforce the connection with a small L-shaped strap from each rail to the valley pan.