My airaid MIT review

[iamdub]

The sound they make is directly proportional to the load on the engine and not just at or above a certain RPM. Ever went up an incline in a car with a manual trans without downshifting? The engine makes a deep growl the more you open the throttle (increased load). The intake does the same but without the mufflers to quiet it. You can ease into the throttle like normal driving and hear virtually nothing different. But if you push the pedal hard from a stop or while cruising, you'll hear the engine sucking the air through the intake and it'll growl.

 

[Brian Wilson]

I her large the difference but I am very car sensitive. and definitely the sound is more pronounced going up a hill or under wide open throttle. if we want to get all scientific, the noise will be proportional to engine timing retard and rpm. the more retarded the timing ( due too gear, load, resistance, whatever) and the higher the rpm, the more flow thru the tube. the more flow, louder sound.