I relocated the SAP to the ECU compartment by the passenger side where the Z3 6 cylinders have it (I'm not sure if this applies to the 318ti or the 318is). I also added a little air-oil separator as suggested by
bkz31998 here.
To relocate the SAP I got the bracket used by the 6 cylinders. It's p/n 41.13.8.401.371 which is #17
here. I had a friend weld the original SAP mounting bracket to it and used self-drilling screws to secure it to the firewall.
I rotated the valve on the exhaust manifold 180deg and further twist it with a pipe lock wrench.
I used a knock-out punch to drill a hole in the compartment wall to route the hose.
And here's the result: