I just installed a FAST LSX R 102 intake on my ls3 with my stock throttle body, at idle no whistle, under a slight load such as going up a hill it whistles, called fast and they recommended putting sealant between the upper and lower sections, so i did, but no change. I can find no vacuum leaks, anyone else experienced this?
I had the same issue but I was using a NW 102 TB. Once I went back to original stock throttle body the whistle was gone. So I found my whistle was from the TB not the intake.
That's weird. My '99 Beemer whistles at idle, and I can't manage to find the source after many attempts--many have experienced the same thing (plastic intake, by the way). It doesn't seem to affect performance . . .
this one doesnt effect performance and only really does it about 1700-2500 rpm under load, weird...think i may try to seal the tb another way than the seal that came with the intake and see what that does.
spray some throttle body spray around the intake while running. If the RPMS change you will know where its coming from. Is it possible the sound difference you are hearing is the difference between the intake and the stock intake with the sound cover over it?