An engine's PCV ( positive crankcase ventilation) system works to allow the engine to breath. Air enters the driver's side valve cover, exits the passenger's side valve cover. The passenger's side is connected to the engine intake to actually draw air through the engine. The "one way" valve...
Not GT500, but have it on my Coyote. Replaced a Twin67. Drivability is the same, lost a little down low, but gained way more on top from seat of the pants feel, as would expect.
After buying the stage 1 kit from AM, then buying upgraded HE, throttle body, etc. from VMP, I wished I would have just went straight stage 2 or 3 right off bat directly from VMP. You will get "safe" tunes from VMP.