Blow Off Valve, circa 2000

"Tuners," speed loving kids of the early 1990s, chose inexpensive compact cars to "tune" for speed and handling. In turbocharged cars, blowoff valves minimized split-second power drop while shifting gears -- if you're racing, that matters. Many of these valves made a loud "whoosh" sound; their bright colors stood out when installed in the engine. Tuners wanted the valves to be heard and seen.