Fuel and air. Both are needed for proper combustion and after you have increased the air with more boost, fuel can’t be ignored. PERRIN™ has now released an easy to install way to keep those upgraded injectors happy! Our fuel rail has a larger center bore than the factory model to prevent injector pulse or lean conditions from lack of adequate fuel reserves behind each injector.. And the extra 1/8 NPT fuel port is designed specifically for external fuel pressure regulators, additional fuel injector feed lines, or maybe some nitrous. Installs in minutes using OEM connectors to eliminate leaks, hassle and time wasted with additional assembly.