The system and chemical agent is made by Wurth, a very well known and high quality German brand of automotive products. It's suitable for common rail and mechanical diesel as well as all types of petrol fuel injection systems.
For the diesel a pressurized reservoir is filled with the cleaning solution and has a regulator set at suitable pressure to suit each vehicle. It's connected after the fuel filter so runs through and cleans lines, pump, injector pipes, injectors and combustion chamber. The process takes about half hour maximum in most cases but some petrol vehicles have difficult access to fuel supply lines and may take a little longer. There is no indication of injector flow before and after test unless they get tested on a flow bench before and after, in which case a difference would be able to be seen. One example is a test Nissan were performing. They measure their injectors on a scale of minus 2 to plus 2. Minus 2 or below is a fail and minus 1 or above is a pass. Many were around the minus 1-2 mark before test and went to plus 1-2 after test thus saving those injectors having to be replaced.
It's a simple operation in most cases as long as fuel supply lines are easily accessible. I have every kind of adapter needed for any vehicles fuel system I may come across.
The petrol version uses a special regulator with pressurized canister of cleaner and this runs on the car for about 5 minutes or so. This cleaned lines, rails, injectors, combustion chamber and intake as well as helps re/lubricate injectors also.
Many dealers are using this system and I suspect the person who posted before me here had the same thing carried out on his vehicle as smoky and hard start up and cold rattles are one thing this flush is quite successful at improving. Here's a pic of the unit for the diesel flush and ill take a video of the next application I perform on a diesel and post when I get a chance.
This is the inline unit for all diesel systems.
Refer to link below for all Wurth VAS products which go into more detail about the diesel and petrol system cleaners as well as fuel additives(recommended along with a system flush) as well as engine flush and power steering flush and treatments which we also use.