Not only MAF readings, but also the fact that usually a cone filter is strapped on, that has a much smaller surface area than the factory filter.
Also, usually the factory airbox induction is carefully optimized to ensure good cool air flow and minimum noise.
When you are replacing that with a shiny pipe with a tiny filter you are not making anything better.
This is all measurable. All you need is a vac gauge and connect it between filter and turbo. Then you know how much restriction it is causing.
Anything less than 0.15 bar is not worth looking at whatsoever.
Yes I know Dmitri, I was just making sure I was on the right page mate. Air turbulence will also affect it, in-fact the maf curve, offsets before it, etc, will be junk, especially on a narrow band car.
There was some horseshit about ME7 needing exctly 3 dyno runs before it 'wrote the flash' or someshit on another forum, it annoyed me....
0.15 bar - is that your findings or Graham Bell or similar? Genuinely interested if you took the time.