Just put it into manual then it won't drop down for overtaking like that. You could leave it in D or S then once your up to speed in 6th knock the gearstick across or just drive in manual anyway as that's the best way 
You are incorrect Weston, even if you put it in manual mode the DSG gearbox will still kickdown unless you have the DSG remapped to stop it.
Kickdown was one of the most annoying traits of the DSG. The reason it tends to take time to kickdown is that it is liable to be dropping two gears, in which case the gear the DSG is asking for is on the same gearset as the one it is coming from ... i.e. 5th to 3rd, 6th to 4th, or more commonly at lower speeds 4th to 2nd.
A single gear drop is usually a quicker change as the box already has the alternative gearset ready to swap to.
REVO and GIAC do DSG remaps which give changes that are up to 60% faster and isolate manual to be a manual ...i.e. no change up at the redline and no kickdown. When in manual the DSG remap still allows the gears to drop to the next one down when the minimum threshold for the revs is reached.
