E67 and PMW the CFCO clutch pin for external rev limit

[TurboStew]

Does anyone have a feel for the ECU response time of the gen4 (E67 or E38) clutch sw input? I have an idea to have an Arduino enable/disable this pin quickly to have an externally controlled rev limiter. I want to do this for rev match shifts in a sequential. My thought was to use only CFCO spark retard and set rpm enable pretty low (1000RPM) and then every 5-20ms enable/disable the clutch input depending if RPM is above or below some threshold. Is there a faster pin to get the job done? I have heard of using an IAT interrupter circuit to look like -50F when active and then set lowest column in the IAT spark table to high retard. I have read this is not real responsive. Any other ideas to have an externally variable spark rev limiter (besides bypassing ecu)?

[TurboStew]

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