Porsche 997.1 Turbo Plenum, OEM throttle body ELECTRICAL (ENGINE) 9 5 (99 09) do88 complete performance air intake ELECTRICAL ENGINE do88 complete performance air intake system designed for an easy drop in fitment in your BMW M2C M3 M4 F8X Bend: 90 degree Inner diameter 1 (mm): 41 mm Inner diameter 2 (mm): 45 mm Inner diameter 1 (inch): 1 5 8 inch Inner diameter 2 (inch): 1 3 4 inch Leg length (see picture): 102 mm Color: Blue Wall thickness: 4 mm Temperature range: 40 to +180 degreeC Outer diameter 1: 49 mm Outer diameter 2: 53 mm Reinforcement: 3 layers Material: High quality silicone rubber polyester fabric The OEM 997 Turbo plenum is T shaped which means the air flow from the throttle body abruptly change direction when it´s divided to each side of the intake manifolds Our plenum flows 34% better for GT3 throttle body and 18% better for OEM throttle body compared with the OEM plenum (see diagram below)