I was wondering about this. Looking inside from the air filter box it looks like its a big restriction to air flow, because its much smaller than the intake pipework before and after the MAF . But searching for info about it or the z32 MAF upgrade I only find stuff about its ability to measure higher flows on tuned cars, no reference to how well it flows itself.
But then I wondered whether the standard MAF aperture size was the same as the turbo inlet so maybe doesn't matter if you are sticking with the standard T28 turbo. Anyone know if this is the case?
Also the SR20 Primera MAF looks very similar to the z32 one and is a tube the full with of the intake trunking, I have one of these spare (I have a primera GT as a 'daily') maybe I can use this rather than the z32 upgrade? Depends if its measurement is exceeded but I think I heard it is well over specced fort the primera (its a non turbo SR20).
Sorry to hijack with my questions, I was thinking of posting these then your post seems to be on the same lines.