I have pinched this off another forum
" The WUR has two funtions it causes enrichment during warm up and then maintains the control pressure on top of the metering head plunger.
How far the plunger moves in repspect of the air pushing against the metering flap determines the air/fuel mixture ratio that the engine gets. The WUR controls this pressure.
The Metering head controls the system pressure, ie the fuel pressure that the injectors see, the amount of fuel that comes out of the injectors is dependant on the position of the slits in the metering head plunger.
So the WUR mod simply alters the control pressure and hence either richens or weakens the mixture right across the rev range. K-Jet often runs lean at higher revs and therefore engines benefit from checking and getting the control pressure spot on.
However you will need a pressure gauge to set it and prefably a gas analyser to see the effect of the change to control pressure. That is why you really should combine the "WUR mod" with a rolling road setup so that you can see the mixture throughout the rev range.
The WUR mod is not limited to the 16V WUR, although it is easy to do with the 16V one. You can modify the control pressure settings on an 8V WUR by drifting the supporting spigot in or out - it is a ball ache because you have to keep taking the WUR apart, move the spigot, put it back together and test again.
"
It appears to be a very good and cheap way of gaining BHP. Other forums go mad for it so Im wanting to get it done!
