That Harrop intake has been shown to produce 20-30hp at the wheels over a FAST 90/90 intake, depending on setup. They are wicked intake manifolds. Like was previously stated, a car with a huge cam will have a much smoother idle with an intake like this as well. There was a video of a car with a Thunder Racing T-Rex cam installed with this intake, but you would have never guessed it from the idle. Throttle response is wicked on this intake as well, something I would think would be desired on a Z28.

My money is that an intake like this could be tuned to pass emissions. This particular intake may be speed density, but GM, even in their current state, has deep pockets. Aren't Chryslers LX cars speed density?