look at the stock tube. it is "ribbed" so it can flex. these ribs make the air path restrictive because of the turbulence they cause. since they are restrictive they make less power/torque. this also applies to the resonator it is made to make the air flow turbulent to make it quieter causing power loss. with the k&n intake the air path is a strait shot to the throttle body (allows it to suck more air because it is less restrictive)
compare these picks and see what i am talking about: Which has better air flow?
IMHO a intake that connects directly to the throttle body and has a smooth air path will give the most power/torque gains.
(BTW the math you talk about are some very hard calculations to many variables)
compare these picks and see what i am talking about: Which has better air flow?

IMHO a intake that connects directly to the throttle body and has a smooth air path will give the most power/torque gains.
(BTW the math you talk about are some very hard calculations to many variables)