That's interesting ...
I have mount a 65 mm throttle body on my +4 GDI + ITG foam air filter and the engine was a bit erratic at idle when cold, when at temperature it was a lot better but still not so good as before.
I was thinking it was due to the throttle by change : more lean until the AFR sensor was at temperature and the ECU able to do the loopback.
Reading the post I swap the ITG back to the original paper air filter and ... Oh surprise it was again as good as before !
I have no real technical explication so far but yes, at idle a simple air filter made more impact that a huge throttle body change
Thanks for sharing your experience
