ITB measurement ??

[Uzelac]

Where to take measure of ITB diameters ?

Someone says measure the opening, someone say measure the exit, manifold side, blade... ?

I had few ITB's passing through my hands and on neither one of them i couldn't find the measures they were specified fore.

Example.

Now i have Hayabusa's ITB's.

http://picasaweb.google.com/uzelac/Hayab...directlink

They all say they are 52mm. Maybe ...because nor opening nor exit have 52mm. Opening is little below 50mm, and exit is around 45mm.
Maybe blade ?

Earlier ITB's i used were from Honda CBR 1000RR and everywhere on internet they were specified as 44mm but on openings i measured ~41mm and at the exit they were below 37mm.

What about AE101 and AE111 from 4AGE 20V engines.
They are specified at 42 (ST version) and 45mm (BT version).
What are they real measures, do anyone knows ?