Hi all,
Yesterday my Evo V developed a weird whistling sound, not too dissimilar to the sound of a Supercharger? The noise increases with revs but mysteriously disappears as soon as the clutch is pressed? The sound pitch also increases with revs but the car drives as it should? The clutch is an Exedy, recent (less than 1k miles), so unlikely to be that. I don't think it's the turbo as that was recently rebuilt by Owen's. Can't see any leaks anywhere so can only assume it to be an air leak?? Any ideas as to where - Intercooler pipe? BOV connectors?
Many thanks

 

My vote is boost leak.

Do a boost leak test. If you don't hear the noise, spray the pipes, hoses, turbo, intake down with soapy water. Watch for bubbles.