Great to see another Z4 with upgraded cooling on the drivers side. Sad to see that you didn't take any of the recommendations I spent so much time to develop on track during last year.
I used to run this exact setup. 7.5hd, csf rad, stock oil cooler, second oil cooler on the drivers side.
It doesn't work.
I documented everything here on spoolstreet but it is buried deep in my build thread and that track cooling thread by barry. So here's the summery:
Your iat will be fine. Your oil will be fine as well, but still rise as you push. Don't worry about that. Coolant will skyrocket if you push in hot weather.
The csf is way too small, because it is the same size as the stock rad, which is super small even for stock power. Don't buy it. Adding thickness isn't enough. I even downsized the fmic and went up to 8cm in rad thickness at one point. Limited ROI there, and iat skyrocketed. Also forget about water wetter etc.
After way too many revisions, I ended up increasing the surface area of the water cooling system by adding two aux rads, and that helped alot. So I highly recommend running an aux radiator rather than an aux oil cooler. What they did with the 1M was right. Here's what I did:
View attachment 36777 View attachment 36778
The 7.5hd is great though... I only went with the ER comp fmic (M235i version, not PnP btw) because it allowed me to install an aux rad behind it. They both have the same frontal area, the ER just isn't stepped like the 7.5.
Anyway none of this matters on the street or on the drag strip.