Daffy
Enthusiast
When I just recently installed my K&N's and smooth tubes I noticed my car has both a sucking sound & a whistle under acceleration. A few days later after installing the belanger catback it beame less noticeable, but only because the exhaust note is louder. JonB told me before purchasing, that the K&N's would make a difference in the intake flow that I would "hear". So, I'm assuming that it's normal.
Dave.
Dave.