Hi revjames, that's a brilliant response. My Disco is a '98 with EDC, it has had the EGR blanked off the intercooler pipe changed, it currently has a cat in the downpipe so I was going to replace that with a downpipe from Paddocks without a cat.
She runs well but you never know if, with a little money and time, she will run EVEN better. So, as I said I will change the downpipe and go the K&N route and see what that produces.
The funny thing is that with my wife's Tdi 200 I drive that like a granded in an invalid car, but with my Tdi 300 it's quite nice to drive a little quicker - not crazy just a bit quicker.
Re the injection pump I suppose there's nothing I can do (as it's ECU controlled) except change/remap the chip?
I also like the idea of everything running to it's optimum.