With new and improved styling, the WS-RFL remains true to it's roots - it's still really f'n loud! Like all our valves, the RFL relieves compressor pressure surge caused by changing gears or backing off the throttle and has been used on turbo charged engines running upto 35 psi boost. If you need to ask how loud it is, this valve is too loud for you! This blow off valve comes everything needed to install to a 2002-2007 WRX or 2004+ STi.