I got my plenum installed yesterday -- it seems like between 4k and 5k there is this weird noise.... kind of sounds like a fast vibration (not very loud, but noticible to me)...

anyone else have something similar or read about something like this?

 

I've had mine on for a while, but I've never heard what your talking about. It has a different idle sound (as reported by others), which I found out isn't present on G_money's sedan and his crawford plensum with a grounding kit. Of course the RPM range you speak of is smack in the middle of when my Injen intake sounds off. And now my exhaust system sounds way louder than that.

"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt

 

hmm :/ I took it to a shop to install -- my friend says im just being paraniod......... any other ideas?

 

I had someone else hear the noise and they said ti kind of sounded like a lower pitch rev... :/