Car manufacturers spend thousands of pounds developing efficient breather systems for their cars, which usually work perfectly okay for a standard model, but once the engine RPM or power output is raised (cams, increased boost pressure etc.) the standard system is no longer sufficient. Bailey breather systems actually separate the oil into vapour and liquid, which gives three major benefits: REDUCED CRANKCASE PRESSURE - Freeing up crankcase pressure by increasing the capacity of the breather and adding more or larger breather pipes, has the result of reducing oil blow-by. This means quite simply that your engine will perform better for longer as the tough job of controlling the oil breathing system is taken care of by the oil separator. OIL RE-CIRCULATION - Because Bailey oil separators are designed to return the oil back to the engine sump, your oil will last longer and the risk of running out of oil is reduced. Oil particles released from the engine are suspended in the air that enters the separator and once separated, the oil is returned through a drain connection to the engine sump. There is also a large bore vent hose that is routed safely underneath the car, to expel any engine fumes. Mix Air and Fuel, NOT Oil - The standard Cosworth breather system vents oil mist back into the airbox, which means that older engines will have a small puddle of oil in their air filters! Engines mix air and fuel to produce power, but introducing oil as well leads to increased chances of detonation, which nobody wants. Due to limited space, LHD Cosworth models & air-con RHD models must use mirror image breather tank. Please note that mirror image tanks only fit with cone air filters fitted.