Some tuning devices seem to list 30 kPa and lower as deceleration areas and some list 20. I would think it should be a standard value. Thoughts on what it really is? Was comparing some documentation by various devices and how they solve decel pop and this shown itself

 

There will be no standard value. Engine combination and location will cause it to change. If you want to know for your bike only at your location a simple test will give you a very close estimate. With the engine at normal operating temperatures use a Data viewing device (DataMaster or similar) and hold the engine RPM steady state in neutral and observe the MAP value at that RPM. Do this every 250 RPM or so from idle to 4500 RPM. Any value less than what you measure would be considered the decel area.