It is not that it becomes loud, it just changes the sound. You would notice a different exhaust note and if your wife drives with the pedal mashed all the way to the floor, she might hear something she did not before? If you installed it and did not tell her, I doudt she would even notice you did anything, except she would get better mpg.

We never applied for a CARB # and do not need to (we are in Detroit, not California), but intakes all pass because they do not impact emmisions when all emission connections (if any) are maintained. Our CA customers have never complained, and worse case scenario is you take the intake off and return it to stock for your inspection sticker, then put it back.

It takes as much time to change to a performance filter as it does to install the intake. Anybody that can read and follow simple instructions can do it.