my 57i is mounted straight onto the plenum chamber above the throttle body, with the airbox taking air from in front of the radiator and blowing it straight onto it with the original pipework, no negative effect at all.
getting as much cold air through the filter is good in theory, but remember that the air going into the combustion chambers is always going to be roughly 60-70'C because the head and the intake valves, as well as the barrel walls and piston crown, are always going to heat it up as it is being sucked in. warm air is going to be better for fuel vapourisation than the coldest air possible, or the fuel wont vapourise properly and stay in little droplets, which doesnt burn as well and chokes the exhaust up after a while.