My 2 cents
Ive read this post a few times and i thought id just put my own 2cents in about CBV's BOV's :
CBV's- COMPRESSOR BYPASS VALVE- come stock with many turbocharged cars. Always plumbed back into the intake tract at some point to keep metered air in a cycle. Normally before the turbo. At idle and non-WOT throttle position, the CBVs DO NOT seal, and leak air back through the intake. ON WOT, the CBV seals to prevent the air from escaping. When the throttle closes, engine vacuum pressure causes the seal open to release the air back into the intake and prevent the air from returning through the piping to the Compressor wheel of the turbo. With a pod style filter on, you can hear the CBV open when the throttle is released. Regardless of transmission type- if the throttle is released quickly air will be vented through the CBV. Therefore, CBV's should only be used in a plumb-back setup.
BOV- BLOW OFF VALVE- Can, but not always, be vented to the atmosphere. Some are designed with trumpets etc to make nice noises, and others are designed like a CBV to plumb back into the intake tract. BOV's have a spring inside to ensure that the valve is sealed ALL THE TIME and should only open when sufficient engine vacuum causes the valve to open. Many BOV's are adjustable to change the rate of the spring, and therefore adjust how much vacuum is required for the valve to open. Setting the valve to a 'soft' setting will make the valve behave similarly to a CBV, in that it may leak at idle an non-WOT position. This is what causes poor running and stalling in AFM equipped cars. Setting the valve to a 'hard' setting keeps the valve sealed until there is enough vac to open it- ie, on rapid throttle release. In this case, however, compressor surge may occur when there is not enough vacuum to open the valve, but the throttle is closed quickly. On a blip of the throttle, you may get a 'ch ch ch' out of the air filter, which is compressor surge. On a WOT blip, you should get a 'pshh'. If that makes sense!
You should be able to try this on any AFM car, and i have many times before. With the engine at idle, if you loosen the BOV you will eventually find the car will idle badly. Similarly, adjustments can be made by tightening the valve a little and then testing my revving the motor to see when it vents.
Assuming the valve is adjusted properly, there should be few problems with fitting a BOV to an AFM equipped car. It may run a little rich when the valve vents, but if it is adjusted propely, it should only be venting for a very short amount of time.
Hope this helps a bit
Cheers
Chris