The 1NZ-FE ECU can account for more airflow, so some people in the US have had success putting a bigger throttle body on... so I thought I would try it.
The part you need is a DRIVE BY WIRE (NOT cable!!) throttle from a 1ZZ-FE (found in ZZE122 corollas) the drive by wire setup is found on the facelift ZZE122's only.
(if you get the part from the US, i believe a scion XB th can be used also)
You need to perform what is know as a 'chip swap', which mean removing black plastic chip/sensor from the top of the standard yaris throttle body and putting it on the new corolla body.
If you dont do this, the car will not run properly.
All you do is drill the rivets on both bodies, and swap over the yaris assembly.
The throttle body will then simply bolt on to where the old one was, if you like you can also do the coolant bypass mod at this time.
You then need to flip the original airbox hose around so it will fit on the new throttle body.
There is a noticeable improvement in mid-high range torque, and a lot of intake noise if you have a pod.
The stock TB in place
The new TB in place
Size of the new TB
Size of the old TB
The old and new...
all done (bar some hose clamps and vacuum lines)