Z4 35i manuals were fitted with the GS6-53BZ. Once again, the 1M got the GS6-45BZ. It is not the same. It is lighter, has less fluid capacity, different synchro material (hence the fluid mixup).
35is were DCT only. Unless manuals were USA only, which I can't find any reference for?
Clutch is definitely not the same, PR delicacy for sure going on here. Pressure plate is 100% different between 335is and 135i/1M. The clutch kit is the same part number for 1M/135i.
The only thing in the drivetrain that is unique to the 1M is the flywheel and programming (beyond the M button). There is no throttle dampener rubbish. Refer to this thread:
https://www.e90post.com/forums/showthread.php?t=1610143
Let's revisit some more PR delicacy here. No manual for the Z4 35is was because the trans apparently couldn't handle the increased torque and overboost
Yes, the same 53BZ trans that is becoming popular for other platforms such as the MK4 Supra where the V160/161 is no longer feasible. The same trans that is much more stout than the 45BZ
in the 1M which also got the N54B30T0.
Another funny note, they limited PPK flashes for the 135i/335i DCT and manual to 317ft/lb. The same DCT is used throughout and on z4 35is, no idea about the clutch-packs.
Point is tangible evidence of what is actually on the car, or part numbers in their own catalog is the truth. Not what what director said for journalists; and the potential(real) misinformation as it filters through journalists, enthusiasts, owners etc.