I know that one of the most effective mods one can do to their Max is to replace the stock intake with a more efficient one, such as the Berk w/ K&N filter.

I am also pretty sure that replacing the original filter w/ a hi flow filter, but leaving the intake stock might result in better mpg, but not much in the way of noticeable horsepower.

That being the case, why does Nissan, and other car manufacturers put it the monster air box instead of something along the lines of an after market intake?

 

IMHO - because the car is built for quality, reliability, and to be quiet. The design they've provided meets those requirements.

 

under hood cone intake can be loud and might loss some torque in a hot day. even the 350z is using the same style of intake system as maxima..(except their front scoop is huge! u can have a cat stuck in it)

Nissan will make something that's durable and efficient, so they dun have to hire too many ppl in customer service to hear complaints.

 

I don't think the intake is all that good of a mod without freeing up the other side

Yes stock intakes are for the majority of the population which is quiet, great filtration and functional without major drawbacks such as torque loss.