ive noticed breather filters online and in stores and im woundering what their for and if they can be used on stealths? whats their purpose and where can they be installed on a stealth? are they street legal?

 

They are normally used in place of the pcv's on the valve covers (like on V8's). I'm not sure one is made for our cars since the pcv is on the side of the valve cover. They are legal but aren't really necessary. I believe they are intended to keep any oil from traveling through the pcv back into the intake tract.

 

If you are referring to what looks like "mini open air filters" they would not help our cars. They are to ventilate the blow-by gasses from the crankcase. As the Positive Crankcase Ventilation (PCV) valve already does this in a more efficient manner it is not needed.

Older, pre-emmision control cars did not ventilate the gasses blowing past the rings alowwing pressure to build up in the crank case. This has a negative affect on engine performance. To remedy this breathers were added to the valve covers. Ideally, a vacuum in the cankcase is best for performance. The PCV valve uses the vacuum in the engine intake to draw out these gases and reburn, much like the EGR (exhaust gas recirculation) valve. No it is not needed for our cars and since it would eliminate part of the emmisions control system, may not be legal for modern cars anyway (depending on local emmision laws).