Yeah if you're getting that hollow rattle sound, it's probably broken. Check inside the manifold for any missing pieces. Most times, the vacuum leaks that result because of the DISA, isn't necessarily the DISA itself but more or less the seal around the DISA. On my '06 3.0, it's a round red rubber gasket. You can choose to replace just the gasket or reinforce it possibly using a gasket maker.

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2006 X5 3.0L - Schwarz Black/Truffle Brown
Stock
But I keep it clean