[hayden55]

Well the whole reason you tune exhaust is because you are attaching exhaust ports together that are firing with uneven pulses, so when you hook them together you balance out each stroke and the next stroke effectively pulls on the other. Adjusting pipe diameter after the header is just what diameter pipe is needed to flow the horsepower you are making. Too small you lose power, too big you don't much of anything. And back pressure needed is a myth for the most part, i've never seen a v8 (in my purpose) lose power from to big of an exhaust they usually just end up spending money to gain a lot of weight and a minute extra lil bit of power. So unless you are tuning an intake manifold runner length or diameter or adjusting throttle body the size of the tube wont make a big enough difference. So i'd assume the air intake tube itself would only be the same cfm to flow horsepower as the exhaust was, more than you need, you don't gain much of anything, less than you need you lose. (But that was all to make power and making power isn't always the most efficient way to tune an engine for fuel efficiency.) Then it just comes down to whether you get a nice strong smooth readings on the maf, and iat's for the purpose intended (power or thermal efficiency). But... It could be down to volumetric efficiency at bsfc. So maybe if you tuned the intake to only pull the air in it need at peak bsfc you would gain efficiency at that point, but lose power up top? I threw all my thoughts in here so somebody correct me if i'm wrong.