an aftermarket intake manifold and large throttle body on a NA engine with no internal modifications (otherwise stock) will result in a huge bogging problem at low to higher portion of the mid-range rpm - might make a little more power at wide open throttle in the upper rpm range - problem is that you can't run it at the very top of the rpm range all of the time - at lower rpm, it will get more air but the velocity of the airflow will be slowed way down and with the larger volume of air, it will just bog - in order to take advantage of the increase in air, you will need bigger camshaft(s) and probably higher compression ratio - if you get the air into the engine, you have to be able to do something with it