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  1. Induction 2-3k rpm whistle

    Focus RS Discussions
    I've been searching on this topic and so far no one has any input. Mountune, local shops, etc. No matter what air filter I have in, there is a steady mid tone annoying whistle from 2-3k rpm. Is this the induction system, air filter, turbo? I doubt it's the turbo, I have the suppression chamber...