hello I currently drive a 1998 Honda civic ex (d16y8) , I recently purchased a header for it and this is a 4-2-1 setup which comes with a down pipe. Recently there has been this annoying noise like a buzz , or if you have heard a car run with an open down pipe then you know what I mean. This sound barely started happening about 3 days ago , I want to know what it is , I have went under the car and searched for any holes in the exhaust and did not find anything , so then I went to check were the down pipe connects to the catalytic converter to see if any of the two bolts were loose then I found nothing was wrong with them , I am wondering if the donut flange is bad because I did have to take the downpipe out once and I did put that same one back on , or if the cat is going bad , if you do know anything about this or have had this issue as well please help me any advice or tips thank you.

 

Make a video of the sound and post it please.

 

I will do

 

If it sounds like an exhaust leak, guess what? It's probably an exhaust leak. Safe bet is that you bought a cheap header. Two piece header? Is there a gasket between the upper and lower sections? Are the flanges flat and seated? Did you use a new exhaust manifold gasket? Did you remove all of the old one?

 

Yeaa it's a cheapie header , and it sound like it's coming straight from the downpipe I have a video to show what sound it is

 

Realistically, I'm not sure how much a video would help.

Also, I asked 5 questions. You answered 0. Care to answer some of those, or do you just want us to waste our time spitballing?