[RarlyL8]

The only time the TBV has noticeable effect on turbo spool between shifts is when it is malfunctioning and hanging the idle. This is what I described earlier that I do intensionally with my right foot, hang the idle between shifts to help maintain momentum of the spool between shifts. The idle drops faster when the TBV is removed so the desire to manually over ride is increased. This is a bi-product of the TBV's function to reduce chop throttle exhaust gas burn. You can see this in action yourself when manually hanging the throttle. The burble or pop is eleminated just as it is by pushing in the clutch.
A faulty BOV can manifest itself in ways that are sometimes blamed on the TBV, and vice-verca, such as the jerky "engine brake" or "teeth in windshield" as Goran calls it. Many CIS components do similar things, have similar functions, which can hamper troubleshooting.