Hey i just bolted a 4-2-1 header onto my 96 civic dx d16y7 but i just ordered my highflow cat so it just goes to a test pipe right now and no cat also my second o2 sensor isnt attached because i need to buy a new one and extend the wires to the bung on the high flow cat. Could this be why im getting no power? Because the 02 sensor isnt attached or because i have a test pipe instead of a high flow cat? All i know is it is installed correctly and the its really loud i also get backfire with it and im not sure why. I need to know if hooking up the 02 sensor will get my power back or if i need to do the cat as well. I torqued them all down to 25 and im almost positive the 02 sensor has something to do with it because it talks to ur ecu also it smells bad it supposed to for the first little while like u can really smell the fumes when i rev it and sit in the same place its also putting out white smoke. Please let me know thanks