Originally Posted by Brendan

Place the dump valve as close to the throttle butterfly as possible! that is the best thing to do!

This minimizes the amount of stationary / stalled air to move next time you open the throttle when the turbo is spinning quickly.

The idea is to keep as much air flowing as possible when you come off the throttle, when the turbo is spun up. Also this limits back pressure and stress across the spindle & turbine blades!

This means the turbo is never pressurizing against a dead end of a closed butterfly!