sounds like the problem i was having with my K&N series 63 on my 5.4L. Its resonance. I bought some sound deadener and wrapped the intake tube and the intake box, and it knocked about 75% of the sound off. Only acts up when I floor it and rpms get over 3500.
Originally Posted by backwoodskansas
Sorry it took so long. Still no fix. I had an air intake on my last truck so I understand the increase in noise, but this is not a whistle, it is a loud "grumble" Took the whole sytem off and tried again and had everything tightened. Any time the engine is close to shifting or rpm increases you can hear the sound. As soon as I let off, it is gone. man this is driving me nuts.