i gave my car and emissions test in class a couple of weeks ago. All the numbers were dead on what they are supposed to be except the one that measures unburned fuel. That was almost double what it was supposed to be. The instructor said it was either my cat converter or i was running rich. A few days later someone else brought in there civic hatch to put on a performance exhaust. He told me i could have his cat he was taking off and that it still worked. The cat i got from my friend was a little shorter than the one on my car so i went to the hardware store and bought some pipe and clamped on the "new" cat. My car now sounds raspy. I can hear the noise comming from the cat area but idk why it is louder and raspy. i put gaskets in and tightened the clamps good. The cat that i put in had a little bit bigger inlet and outlet but idk if that accound for the noise change. So finally i guess my question would be...Is there anyway to make my car sound the way it did before the cat converter switch?

 

you might wanna try some of that liquid exhaust sealer around the cracks.....