echo Gambit there - sounds like you have received some inaccurate info there - bolting on a DV is straight forward no need for any remaps or additional upgrades - there have been comments in the past about the cars not running as well with them on but that has been going from a standard recirc valve to an external vent, when reverted they were fine.
I have never had any issues with fitting dump valves and they have always resulted in smoother gear changes