There's it on the same web site as your picture-
But they do not have a 6 cylinder one.
http://nagaz24.pl/omegas-4-cyl-harne...1631,p,en.html
or
http://nagaz24.pl/omegas-4-cyl-harne...1630,p,en.html
So the 1st link is the wiring from the plug to the petrol injectors with a male and female plug to match the petrol injector i.e you unplug the car's petrol injector plug and replace with the lpg one and then plug the car's plug into the lpg's female plug.
And the 2nd link is the same with no plugs so you have to cut the signal wire going to each petrol injector and then solder the lpg loom to both sides of the cut.
If you don't have these looms then you have been sold a incomplete system.