I use to have an Injen CAI on my 03 5AT sedan. I decided to go with a different setup for my 05 5AT coupe. My Injen use to sound like a loud vacuum under heavy acceleration. With the Z-Tube/Popcharger I have noticed a ringing, whistling noise under heavy acceleration. Is this normal?

 

its normal, during cold weather the whistling gets even louder. take it out at 2Am and ull see what im talking about.

 

I had also installed a JIC y-pipe and Fuji exhaust at the same time and thought there might be a loose connection. I checked the intake and everything seemed tight, so I just wanted to be sure of what that sound was coming from my car. Do you notice that it lessens when the motor is hot?

 

ya, its normal dont worry about it.

 

Damn, I worry about everything I install. I am not a mechanic. Thanks for the replies.