I contacted toyota and was told the filter is 2.5" but they dont have any more info. I contacted autoanything and was told that AEM intake is 3" for scion tc but they weren't sure about TRD, and I looked at TRD sparks for the installation and size of the piping and it says 2.75". It's snowing and freezing outside, I am looking to replace my filter next oil change and these winter months make it a pain to be outside long enough to take the filter out and check, so if anyone has the TRD CAI can you please tell me which is the right size? I am looking to replace it with the AEM Dryflow filter which I can only find online. Someone help me out so I can order this damn filter already!?

based on TRD replacement filter and AEM version of the Intake it shows 2.5" so I'm going 4 dat. Wish me luck!

please do update us on that. :) I was thinkin about buying a replacement filter too for my TRD. I was about to ask the same question on here haha