The FAST LSXHR 103mm Intake Manifold is ideal for generating maximum power in boosted and naturally aspirated GM LS cathedral port engines. It ships with a set of ‚tall‚ removeable velocity stacks, however ‚medium‚ and ‚short‚ stack options can be purchased separately. This allows interchanging of the various runner lengths so racers can experiment with finding which combination makes the most power in their application. Its polymer construction is lightweight, very strong and virtually eliminates power-robbing heat soak that occurs with commonly available aluminum intake manifolds. The manifold has been optimized to make power from 5,000 to 7,500 RPM, with testing showing 20+ horsepower gains over competitor tunnel ram intake manifolds. The FAST LSXHR 103mm Intake Manifold is designed specifically with boosted applications in mind and is rated for up to 45psi of continuous boost pressure. The compound fuel injector angle aims the spray pattern for ideal atomization, resulting in maximum power production and superior drivability. Also included with the intake manifold are custom fuel rails and necessary hardware. A reversible top allows for forward- or firewall-facing throttle body installations. The intake manifold also features two nitrous nozzle bosses per runner for clean and easy direct port system installations. Additionally, its 103mm throttle body opening can be port matched up to 105mm.