My speedo is still in Kmh at the moment, and I also have a Defi Sports head up display that does speed in Kmh only! I think the car has been de-limited as I can go off the clock.

There are 2 things I don't understand,

1/ Why was the car not converted from Kmh to Mph, I thought this was always done when de-limiting?

2/ How come my Defi gives a completely different Kmh reading to that of my speedo, it seems well down?

it sounds like its been de limited by using one of those cheapo solder in chips, it basically just converts the signal going to the ecu, depending where u have spliced in your head up display to the loom, you could be reading the modified signal going to the ecu rather than the 'clean' signal going to the std speedo.