Features: After installing this product, the pressure blowing from the exhaust will make your vehicle sound like a turbo vehicle with turbo system or blow off valve. Made of high quality aluminum, light and durable. Easy to install on your car exhaust pipe. Installation: 1. Loosen the Turbo Sound whistle screw.2. Insert the Turbo Sound whistle into the exhaust pipe.3. Tighten the screw to avoid falling off while driving. Notes: 1. Make sure the exhaust pipe is large and long enough to accommodate the Turbo Sound whistle.2. Professional installation is recommended, products damaged during self-installation will not be refunded.3. Please check and retighten the screw regularly. Technical data: Color: silver Material: aluminum Size: S, outlet pipe diameter: 32-43 mm, length: 11 cm, capacity: 1000-1600 cm3 Size: M, outlet pipe diameter: 37-48 mm, length: 11cm, capacity: 1600-2000cc Size: L, outlet pipe diameter: 44-55mm, length: 11cm, capacity: 2000-2400cc Size: XL, outlet pipe diameter: 56-85mm, length: 12cm, capacity: 2400+cc Package include:1 set * Turbo Sound whistle