GEeEYah...the misinformation.
ITR and CTR midpipes in terms of diameter are the same. Two resonators. One main, and one secondary right before the axle-back/backbox/muffler (for all our international visitors)
If you have a EJ6 and you can get your hands on an EK9 midpipe and muffler, then go for that.
Otherwise the ITR midpipe will have to have the center hanger modified to fit.
You are best off visiting A&J Racing and looking into the T1R line of exhausts. The motor regardless of 16A/16B/18C can benefit from a 2.5in exhaust - They also had a limited run of their 70mm/2.75in. systems which proved to make the most power at the expense of more noise.