I don't know of anyone down your way that deals with the e-manage??? Come to think of it...they are thin on the ground up here too!
I've been running the zeners for a while now, no problems, I'd recommend doing it even though they say the software is fixed...as the voltage drop over the zener brings the trigger voltage down from 5V closer to the factory trigger voltage.
I'm also 99% sure your checklight will be on, as you have the same coils as the R34..which means the diagnostic system in the ECU will detect the same 'problem'
You can do a fairly good tune yourself using the 'consult' to pull your factory map off the ECU and adjust tune through the e-manage...then just run along to a dyno to check out how you went