I bought a lowered sump from Tiger, which has the windage tray (is that the right name?) exactly under where the Zetec dispstick enters the engine. As you push the dipstick in, it feels like it is hitting that tray and then sliding along the top of it, rather than actually going down into the oil and, in fact, when you pull the dipstick out, you can see the curve in the end of it.
The result is that the oil always shows as at the top mark but I'm not sure if that's real or just the excess oil left on the tray from previously - make sense?
Pic of tray is in this blog post:
https://zerolifebuild.blogspot.co.uk/2015/11/sumptuous.html