Skunk2s engineers looked to the popular 06-10 Civic Si's RBC intake manifold for inspiration when developing our Pro Series Intake Manifold for K-series engines (excluding 06-10 Civic Si) and went back to the drawing board. Each of Skunk2's Pro Series Intake Manifolds for Honda's K-series engines feature larger plenums and shorter, oversized runners when compared to the RBC, and are cast with thicker wall material, leaving room for further porting for high-horsepower applications. Instead of producing a manifold with a significantly oversized plenum and excessively short runners that would sacrifice mid-range power, Pro Series manifolds were designed for the 'street enthusiast' who wants more power but doesn't want to sacrifice mid-range performance to get it. The results are improved airflow, an enhanced venturi effect, and both mid-range and top-end power gains. Skunk2's all-new, cast-aluminum Pro Series Intake Manifolds for Honda's K-series engines are a direct-fit replacement for all K-series engines (excluding 06-10 Civic Si) thanks to their unique, patent-pending throttle body flanges, which are compatible with OEM throttle bodies as well as those as large as 76mm. Pro Series manifolds also incorporate an angled-runner design, which allows for ample hood clearance on '88-'00 Civics and '90-'01 Integras with K-series engine swaps, as well as additional core support clearance on '02-'05 Civic Sis. Pro Series Intake Manifolds offer horsepower and torque gains greater than the popular RBC manifold but without compromising mid-range power output. The design incorporates runners that are similar in length to the RBC's but with larger bores, a special tapered design, as well as a larger, tapered plenum that together preserve mid-range power but increase and accelerate airflow to allow for significant top-end power gains. Pro Series Intake Manifold runner exits are also machined and hand-finished to best match the cylinder head's ports.