As far as cleaning the injectors that kit is by far the best way to go about it without removing the injectors. The 3.0L might have the Siemens (I think) injectors that have ceramic seats and will be ruined by ultrasonic cleaning.

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1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)