5.0 bar Bosch FPR what exactly is and waht does it do for a KO4 do i need it?

 

5bar is 73.5psi of fuel pressure
fpr - fuel pressure regulator.
It increases the prussure in the lines and increases the amount of fuel an injector puts in the cylinder.

You will need one if your tune calls for one. If it just uses new injectors, then no.

 

A 5bar FPR is also a modified 4bar since they don't actually make a 5bar

 

how will i know if my software needs it?

i have a 98 a4 5 speed if that helps

 

whoever you buy it from should say you need it.......

 

does a pc-16 file need it

 

GIAC PC 16 you will use bigger injectors so there will be no need for incresed fuel pressure to supply the correct amount of fuel.