ok i dont have an itr but what i do have is a civic with a full ctr swap so i think the tech info i need would be the same and you guys would be the best to ask. i got this car with a smashed up dc header with a 2 inch collector. i bought a new header that has a 2.5 inch collector like the oem one so now the hacked up cat that is on my car will not work with the new header, i would prefer to replace it with a cat pipe/test pipe whatever yall call it here anyways. my question is this, is there an o2 sensor after the cat? sorry im not able to inspect it for myself, i really dont have the means but need to know before we put the header on. if not then i will just have my exhaust shop make me a test pipe, if there is, i will need to order a high flow cat before the install of the header so this little question is holding back progress. thanks guys.