It doesn't go in-line between the boost control valve and the wastegate servo it goes in place of the boost control valve.

The recommended way is in place of the BCV but it does and will work in series.

I had to think about that for a while. If you're keeping the stock management system you'd leave the BCS plugged in to keep from tossing a CEL. I thought it would be cleaner, fewer connections to just bypass it. But either way would work as the MBC would still keep the compressor building pressure after the solenoid called for it to bleed off.

I think I get it now!
 

My original assumption was that an MBC valve would be used to postpone the positive pressure from opening the wastegate, and would therefore be installed in-line between the BCV and the wastegate servo, but that's wrong, so:

Tell me if this is right: the green line carries positive pressure from the compressor housing to the BCV. Based on the vacuum from the blue line, the BCV decides how much of the compressor's positive pressure to meter to the wastegate servo...right?

Assuming this is correct, is the metering done exclusively and mechanically by the BCV, then the ECU uses that information to control, for example, the FI's, or does the ECU control the BCV?

So: you use an MBC valve to control the pressure fed from the compressor to the wategate servo, bypassing whatever effect the ECU and BCV might otherwise have on the system.

And you now cap off the unused BCV nipples?