ASM Autobacs / TODA throttle body
 

google translate is not good enough.. :( can anyone translate please?
http://www.autobacs-asm.com/blog/asm...s_view&no=2865

Looks like a bored out OEM unit.

is this your speculation or does it say that anywhere?

Pure speculation. Sorry to disappoint.

hey this throttle body is only 2.3 mm bigger not worth it

This is one of the most basic modifications in ASM Autobacs, but not well known in Western countries. Even a 2.3mm increase in the valve diameter, it makes a considerable change in the circle area. Standard valve diameter opening is 65mm and with the change it goes to 67.3mm. Circle area is 3316 and after change it goes to 3555. Overall a 7% increase.


Additionally, they create a tapered entrance in the throttle body with a maximum diameter opening of 72mm:

http://i67.tinypic.com/2hpsy0w.png

This helps to accelerate air flow even more using the Venturi effect.

I think Subaru has a pretty good idea what the venturi size should be.