Subaru flat 4 turbo engines have similar issues but they have aftermarket solutions-just 1 example:
Air/Oil Separator - WRX/STi/LGT/FXT - GrimmSpeed
The Subie enthusiasts recommend one catch can per bank and water cooling them !
Best STi Air-Oil Separator | How-To Weed Out the Bad from the Good
Interesting to note that none of these manufacturers offer a specific after-market part for Porsche M96.
Aftermarket Air Oil Separator
Back to Boxsters - here is a helpful diy link:
Replace the Air/Oil Separator
https://sites.google.com/site/mikefocke2/airoilseparatorreplacement
There are a few 'hits' where someone crowed about inventing a diy AOS alternative for the M96 but then there is total silence.No "I've done 20,000 miles with it and it works great" follow-up !Beware.