I have a 96 GT, pretty much stock. The only power plant modification that has been done is had a BBK Cold Air Kit installed. Currently when the car is running there is a very loud hissing noise coming from the engine. I have checked the PCV valve hose which runs to the intake, the vacuum reservoir under the right front fender, remounted the intake and still there is this very noticeable and very loud hissing noise. The noise does not change pitch or intensity as the engine turns higher RPMs. I'm at a complete loss as to what this is coming from. Any ideas or suggestions would be greatly appreciated.