probably by running a turbo with VNT.
it is basically a huge turbo (as denoted by the GT20 or GT22 starting numbers), but by changing the vane angle you get it to behave like a small one. so you get high resistance at low rpm with the vanes closed, and low restance at high rpm with the vanes open.
That means it spools as fast as our little GT 15 family units, but are big enough to flow enough exhaust gas and drive the compressor like a fixed vane GT 22 unit. it results in the ability for well over 200bhp - assuming that the fuel is there.
All modern diesel engines now use VNT units, they are the way forward, but they are more fragile than 'old style' fixed ones. which means this like fuelling and boost is much more important to get right early etc.
Controlling it on the L-series is not easy however, but there are a few people trying to do it as we speak. either has to be done via a seperate control module, or tie it into the EGR vavle controller - but for that you have to remove the EGR, so that would fail MOT on a Mk2 as that can't be disabled yet
We are getting there, and this last little bit will be cheaper than the rebuild was for sure
