well the 01+ civics have a different exhaust system... it consist of:
the header, a mid section pipe with an o2 sensor that leads to the cat.. and after the cat there's another o2 sensor.. then the rest of the cat back...

the header I got is an upper section only...

well maybe I didn't connect it too well to the pipe that leads to the cat... I guess thats something I can check out tomorrow.

oh yeah thanks for the idea.