The caller Mica from SFO mentioned that she had a whistle when taking off in her Honda. She mentioned that the previous had installed an air filter kit or something like that. I think she may have meant that they had instaaled an “aftermarket cold air kit”. These kits replace most if no all of the air intake tract, filter box, inlet tube etc. Their intet is to make more power and to give the engine a ore thoraty sound. I have sold these kits tere are many different brands and many of them do nothing and some make whistles and other strange sounds. Mica’s only solution maybe to go to a junk-yard and get all the original parts to replace the aftermarket kit/ or she’ll just get used to the sound!
I agree with this, I’ve heard several Civic/CRXs that whistle with aftermarket intake systems. Not only is there no problem with this, but she has a super cool whistle when she hits the gas… nice!
I agree that the OP’s suggestion makes perfect sense. Altered flow paths for air can make all sorts of whistles. The original designers even design in baffles and boxes to acoustically quiet the intake air. I looked at a Scion xB engine a while back and it had a really weird one designed in. It looked like a plastic test tube sticking out the bottom of the intake plenum.
It’s not always the case to put all the blame on aftermarket parts though it might be the case… There are really good brands of air filter out there and so let’s not make any generalization on the aftermarket parts…