Basically, you are virtually attempting to reduce the volumetric efficiency of your engine by making the air less dense - not by reducing the volume of air, but the mass of air, and hopefully reducing pumping losses in the process.
Have you thought of the effects of increasing the humidity of your intake air? I know, I know, water injection has been discussed to death on this forum and it has no effect. But what if you combine it with a HAI?
Here is a link to a dyno correction calculator that I have been playing around with:
Relative Horsepower Calculator
Here are some calculations that I have tried (assuming this calculator is accurate, which it must be because it's on the internet!
):
BASELINE
Air Temp: 70F
Barometric Press: 29.03"
Relative Humidity: 0%
Elevation: 0 Ft
= 100.0% Relative Horsepower To Rated
INCREASED AIR TEMP
Air Temp: 160F
Barometric Press: 29.03"
Relative Humidity: 0%
Elevation: 0 Ft
= 91.2% Relative Horsepower To Rated (not a huge difference)
INCREASED HUMIDITY
Air Temp: 70F
Barometric Press: 29.03"
Relative Humidity: 100%
Elevation: 0 Ft
= 97.0% Relative Horsepower To Rated (Less of a difference)
Now...wait for it.....
INCREASED INTAKE TEMP & INCREASED HUMIDITY
Air Temp: 160F
Barometric Press: 29.03"
Relative Humidity: 100%
Elevation: 0 Ft
= 57.8% Relative Horsepower To Rated (HOLY MOLY)
However....I see a problem for us folks with automatic transmissions. Having a larger throttle angle is going to make the transmission quicker to kick down to a lower gear. Maybe steady cruising in high gear will be impossible because the tranny will keep kicking down. Our electronicky cars don't have kickdown linkages to adjust either. Maybe this doesn't matter, who knows.