Skunk2s 84mm - 90mm Big - Bore Throttle Body Cold - Air Intake Coupler allows for easy installation of Skunk2s '06 - '11 Civic Si Cold - Air Intake when using a Pro Series Throttle Body or similar (also compatible with OEM TL throttle body). Simply replace the Cold - Air Intake systems included silicone coupler with Skunk2s 84mm - 90mm version for a simple, factory - like fit.