With new and improved styling, the BOV-H-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! Blow Off Valve Type H-RFL comes standard with both a mild steel and aluminum weld-on adapters. Bolt-on kits are available for most OEM turbocharged applications.