That was my thread.
We converted my friends Z4 35i to 35is tune. worked a treat, and is a good upgrade for stock.
Write the 35is bin as a Custom Flash.
you will note once its done, the Current Software: will read a number ending in 2514. ( i believe the full number is 8652514)
MHD uses this number to create its OTS flashes, depending on what you choose. You ca even select "Flash Back to Stock" and it will write the stock Z4 35is file based on the 8652514 ZB# that is now recorded.
Both myself and my mate (
@Osiris ) have played with this at depth, his orginal file was an IKC0S ROM, an on JB4 and MHD Stg2+ he could never boost correctly, we dont know if the file was just placed on the car incorrectly after it had a single turbo from the previous owner (which i believe to be the case), but after i converted him to the true INA0S ROM from the 35is, he had been running a Custom tune for years based on the 35is bin, Id been begging him to now try the Stg2+ OTS map to check that his boost issues were a thing of the past, and true to word, they were. car holds boost as it should.
Its my belief that MHD focuses on the main ROM's. (I8A0S, IJE0S, INA0S and IKM0S).
the IKC0S ROM that was on his Z4 initially was VERY close to INA0S, and i think that MHD reads it as INA0S due the extreme similarities, the car ran and drove perfectly fine, just didnt reach correct boost, and had more timing corrections than usual. (Timing Main table did not correlate correctly to the INA0S XDF on his "stock" bin).
I can say without a doubt that upgrading and converting your Z4 to a 35is tune, and using that as your stock base going forward will be best thing to do, yes, the OTS maps are largely generic and yield similar power results for a multitude of N54 cars, but, knowing that you have a solidbase to work from should you go a custom tune int he future, is a plus initself.
Good luck mate.