Ok, so I made the same mistake again, for some reason I thought that the car had been running fine before the timing failed, so everything else should be ok. I was wrong, of course.
Luckily I borrowed a Mityvac vacuum tester for some other purpose from a friend, and I thought I check the components of the secondary air injection system, or SAI, just in case. The vacuum reservoir tested out fine, it holds the vacuum perfectly.
The change-over valve failed though.. Vacuum should open a diaphragm inside which opens a valve for the air flow. This one here does nothing.
It looks surprisingly clean inside.
Ok, this is where the vacuum escaped..
The next component in the system is the check valve. It`s a simple rectifying valve that won`t let the exhaust gas going backwards toward the check valve. I blew some air in it, went through freely from both sides. Not a good sign.
Inside. Not too healthy.
Both the check valve and the change over valve cost over $100 each. Great... After some digging, I found an old thread with some excellent info about the Mercedes SAI being very similar to the Boxster`s. After subtracting the Porsche tax, they came out much cheaper.
Check valve, porsche vs. Mercedes. They look identical.
Change over valve, Porsche (left, destroyed) vs Mercedes. The vacuum line inlet is rotated 90 degrees and the housing is plastic instead of aluminum, but it`s made for the same purpose in a German car, so it should work. Thanks, Particlewave, for the tip!
Boxster
Next time before I buy a car, I`ll look into the forums and if I see too many acronyms I`ll just walk away 
Hybrid Mode
