So heres the deal, I got a FMIC from a friend of mine off his B5 and some how made the piping fit on my b6, might be kinda WEIRD looking and SMALL but it works ...



Anyways... After I installed this FMIC, everytime I start my car "cold start" this noise comes on, sounds like a high pitched air plane in my engine bay, and after my engines idle goes down the sound stops, OR if i turn my car on for 10 secs and then turn it off and back on the sound goes away and my idle is normal like it never happen and this is ONLY on cold start, everytime after that it never does anything, I have an idea of what it could be but I wanna hear opinions...

This ONLY happens when I have my FMIC on, when the SMIC is on this does not happen at all. Im confused on whats causing this. All the piping is on properly, no leaks.... IDK...

 

It may be just the piping seeing as the replaced piping is aluminum and may cause some kind of resonance...