The front mount heat exchanger plus air-to-water charge cooler both should be upgraded in order to see the benefits from cooling mods. This is from the context of what I learned from the F8x platform.
So unless BMW drastically improved the cooling for the S58 over the S55 then I'd say you'll want to upgrade both components. Where's the data? Here you go:
Data log results: EOS Charger Cooler + Awe ColdFront Heat Exchanger
https://f80.bimmerpost.com/forums/sh....php?t=1908740
I've also added methanol injection to the above mentioned cooling mods and now see IATs 10-15F below ambient when I dropped the hammer.
In summary, it is the combination of these 3 upgrades (I've found for the S55B30) to be highly effective for cooling.
And lastly, if you run a cooler burning fuel such as E85 … I've found that my EGTs have been as low as 350-400F during WOT.
Hope this helps