that 1 psi = 15hp is a Very broad generalization... is that 1psi at ambient, or STP or at 40 lb/min or what?

i dont give much creedence to ram air these days... just cool air. cool air is much more plausible than ram air. the dynamics and physics of having an actual functionl ram air intake beyond the cool air supply is not easily achieved.

your gas mileage probably increased because you have a denser intake air charge so you have a better combustion meaning you can get more power for less throttle input and fuel consumption... so id say your BSFC has improved slightly. id say youd have to be moving Pretty fast to see positive manifold pressure w/ a ram air intake setup. plus, convincing the air to "ram" past your air filter is going to be challenging at best.

any track times?