Porsche 997.1 Turbo Plenum, OEM throttle body ELECTRICAL (BODY) 9000 (86 98) Hydraulic Engine Mount Rear OEM 1580 cm3 vs 1050 Hydraulic Engine Mount Rear OEM SAAB Inner diameter 1 (mm): 76 mm Inner diameter 2 (mm): 89 mm Inner diameter 1 (inch): 3 inch Inner diameter 2 (inch): 3 1 2 inch Length: 100 mm Color: Red Wall thickness: 6 mm Temperature range: 40 to +180 degreeC Outer diameter 1: 88 mm Outer diameter 2: 101 mm Reinforcement: 5 layers Material: High quality silicone rubber polyester fabric During the development process of this plenum we spent a lot of time with flow simulations of the internal Y shape design The results of the final design were very impressive the do88 Plenum totally outperform the OEM Plenum by 34% increased flow at the same pressure drop