Sam's 2.0 16v VNT ph1 rep HDi

[Ruan]

I'm guessing its due to light springs in stock applications to keep friction losses down and they can get away with it as the engines dont need lots of revs as they're a modern diesel with modern turbochargers.

And that most modified engines are running much higher pressures in the ports which can hold a valve off the seat?

Nothing to do with revs really, rather just exhaust and inlet pressure causing the valves to float.