If you want to double the volume of your ztube mod...try removing the 3" piece of plastic from the airbox that has "POWER DUCT" written on it. It's held in place by a couple plastic rivets...just pop them up from the bottom of the rivet. I used the handle of a hammer to pop them up. You can always stick it back on if you don't like the sound.

You won't gain any power..you may even lose 1-2 hp since it's prob sucking in some hot air. But i'd say the popchargers are sucking in the same hot air. The sound is a real kick...especially from a 4door family sedan. People wonder what's under there

 

So the whistle is coming form the K&N allowing more air flow??? That sucks.

I haven't tried this, but would the same sound occur if you used the stock tube w/ the K&N?

 

Been running Z-tube/K&N for 6 months...recently installed Stillen CAI....WOW what a DIFFERENCE!!!...if your looking for insane noise at high rpm's go with the Stillen CAI...It gives a nice raspy sound..also sounds a little like the coupe... no joke...Stillen CAI all the way