Simulating ignition coils for factory ECU BMW E92

[USAdude]

I'm going to take over ignition control on a 2007 BMW 335i (N54 engine). I am using M800 for supplemental port injection control (factory DI). I've been told to use a "choke" so the factory ECU stays happy and thinks there's still coils installed.
Is there any more information or other solution?
Where to buy? Part number or details?

I'm not sure what to expect,.. to me this is uncharted waters.