I could be wrong, but I don't see how anything before the DISA valve can effect the operation of the DISA valve, up to and until you add forced induction. Then, DISA is a problem. If you do not modify the function of the throttle body, I don't think you can drastically change the characteristics of the airflow past the DISA.

DISA adjusts the length of the intake runners based on the MAF and throttle sensor, or some derivation of that. There are no MAP sensors on early M54...so pressure or "balance" isn't really a thing, I shouldn't think.

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2001 E53 3.0 5pd