The LSXHR™ 103mm Intake Manifold for LS3 Rectangular Port Applications is the industry's first polymer tunnel ram-style intake manifold and is ideal for generating maximum power in boosted and naturally aspirated engines. Standard "tall" stacks are interchangeable with separately purchased "medium" and "short" stacks to find the most powerful combination. Polymer construction is lightweight and high strength to eliminate power-robbing heat soak commonly found in aluminum intake manifolds. Average 30 HP gain between 5,000 and 7,500 RPM over competitors' high ram intake manifolds. Rated for up to 45psi of continuous pressure. Compound fuel injector angle aims spray pattern for ideal atomization, resulting in maximum power production and superior drivability. Reversible top allows for forward- or firewall-facing throttle body installations. Two nitrous nozzle bosses per runner for clean and easy direct port system installations. 103mm Throttle body opening can be ported to 105mm.