Does anyone know how you can put a full exhaust on a civic lx without fucking it up? I have full exhaust,intake,header,am cat, and cat-back exhaust. I am having problems with the o2 sensors tripping my check engine light on, so i cant pass emissions! The place that i had it done at said i would have NO problems with my emissions. But now they are saying that they think the only way to fix it is to go back to the stock header and cat. Does anyone have any ideas? If i go back to stock header and cat, only keeping the cat-back greddy, will i just have to eat the 400$ i spent on the dc sport headers and the cat? Should I have to pay for something that wont be on my car because of their mistake, because they assured me it would be fine????? any advice would be great. (installed the full exhaust maybe 4 months ago)