Hey guys,
Did a bit of digging and couldn't find one conclusive thread confirming this so here I am doing it. For those who care or are curious in doing this you CAN use BMW 135i Brembo rear brake callipers on your E9x 335i or 330i.
There are two items to note:
1. You'll need to slightly bend (completely replace your brake dust shield if you're THAT adamant on doing so).
2. You will need to use the M Performance rotors (Product Number: 34216795755 ) intended for the 330i on your 335i which are several mm smaller in diameter.
From my research the 330i and 335i share the same brake assembly for the rear so these parts are interchangeable. Handbrake functionality is fully retained. In my case I'm also using the F30 front brakes and need to bleed them once more. I'll be posting a follow up later if you need to completely swap out the master cylinder but in the meantime pics and video below:
