I went with the front kit from Freaky parts which are stock 4 pot calipers off of Renault Megane RS Trophy R and also Porsche rears.
https://freakyparts.co.uk/collection...-big-brake-kit
Mind you I have not tried to put the stock wheels on. I am running Apex SM-10 and these wheels have plenty of clearance.
So far so good. Stopping power is really good. No fade on track with RBF600 fluid and Hawk HP+ pads. And also the cool thing about the pads is that these calipers use a very common pad shape that is also used on STIs, Evo, even the new Civic Type R I believe so they're fairly cheap and available. The larger front pads cost less than my "porsche" rears off a non-s boxster :/
If you notice FP also offers a 360mm rotor kit which is basically same just a different bracket, however I can confirm it does not work on Z4M. The rotor hat of the 360mm E92 rotor has a different offset, it goes deeper and rotor hits the tie rod ball joint. Cannot even bolt it on. It can be done on M3 though.
Pad changes do not require you to take the calipers off which is also a benefit for quicker service. And also the pads sweep the rotor end to end, no rust ring. I did order the cheap brembo pads that come with this kit and had them on for a bit, both street and track. Conclusion: they're quiet, have quite very good stopping power for spirited street driving but on track after 4 x 20-25min sessions and more than half of pad is gone and they started making weird noises and making grooves in the rotors (it sounded like really bad resonant squeal on hard braking). In other words these are great but for street only.
And another option:
https://www.vagbremtechnic.com/front...lipers-bk0014/
Nice writeup here:
https://thebuildjournal.com/reviews/...e46-m3-review/
These calipers might be slightly bigger than Brembos mentioned above however I am not 100% sure. The difference is the FP kit has 4 x 40mm pistons, and the ones off Aston Martin DB9 have 40mm and 44mm pistons. So even more piston area to work with. But these are also more expensive
Either choice is better than tried and true Porsche option in my opinion.