355 lets discuss the vacume system

I think you are correct. I'm not sure what the second air solenoid valve that goes from the vacuum source to the exhaust tube does. The check valves would prevent them from acting like an EGR or would they?

 

Right image:

Vacuum comes from throttle bodies and goes through valves (20) into a hose (22). Two hoses/valves on each side of throttle bodies join into one vacuum line that runs to the vacuum canister which is an old tomato can (left image, 6) susceptible to rust and deterioration.

On the left image:

Vacuum gets stored in the tomato can and runs down to the two solenoids (8) through a rubber tube with a junction (11, 10, 9). One solenoid (on the right) lets air go to the pump which makes a loud whining sound on startup and pushes air through an overly expensive metal pipe to the cats for some bull**** emissions related crap. The left solenoid takes vacuum (at certain rpms, gear, and throttle input) through a rubber tube (35) to the aforementioned overly expensive metal pipe (36) (via a nipple which can become brittle and crack off) to another rubber tube to activate the stupid bypass valve which makes the quiet exhaust louder, even though it's a Ferrari and should be loud all the time.

That's my in-depth explanation from what I remember. Other notes:

-Stock bypass valve needs 10hg to open
-Plugging the valve port on the bypass valve with your finger should barely hold the valve open, and you should feel suction, that is good. The valve won't stay open because your finger isn't providing continuous vacuum
-6-8hg on idle is normal, it will spike with throttle application and instant release
-Individual throttle body setups suck at providing vacuum
-The vacuum reservoir cannot provide enough vacuum to open the bypass valve on a cold start, you need to wait a few minutes (however, you shouldn't be providing that much throttle input on a cold start anyways...)
-The air pump has nothing to do with bypass valve operation, it is pushing carbons out on cold starts and eventually shuts off
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Fantastic explanation!

You say I one solenoid let's air go to the aux pump. Do you mean the vacuum activates the solenoid which in turn activates the pump? Is it the vacuum that determines how long the pump stays on for?

 

One solenoid operates a shut off valve for the secondary air pump output and the other operates the bypass valve

 

I don't believe so. The pump supplies air to the secondary injection system, I believe that is all.

 

From all my bench testing, these solenoid are just simple boost type valves. They either allow flow thru one way or another.