Downpipe Noise Issue

[BlankWoody]

I installed a new 4-2-1 headers with a down pipe. The rest of the exhaust is an Apex cat-back. First week of having it, it was great and all. I added a resonator to help with the rice. Now after the 1st week I started getting a noise coming from the manifold area. I'm not sure if it's with actual headers or down pipe. If i'm going uphill or driving in a leveled road and i try to accelerate it starts making a noise and i feel it right underneath the drivers pedals. It'll stop only if i let go of the pedal. Now ever since that happened my rpms aren't on point. If I'm in D4 the max my rpms will go to is 2.4k, If I'm in D3 rpms go all the way to 4k. You can see the rpms struggle to increase. I haven't received any CEL codes regarding this. Do you guys have any idea what's making this happen? I looked on google and all over the forum. Couldn't find a similar problem or noise. The noise sounds like something is stuck in the exhaust stuttering.

 

[james'99]

Are you cat-less? After putting on the header, did you clear the codes/monitors so that the computer could re-learn the new parts?

 

[BlankWoody]

I installed a new cat at the time. Yes I cleared all the codes/monitors after I installed the parts.

 

[james'99]

Have you ever seafoamed your car? This may be a good time to do it. You'll see white smoke come through if you send it through the vacuum lines. White smoke should seep through any leaks. If under pressure, there is a significant leak between the header and head itself, you may have a considerable decrease in perfomance due to the non metering of that air by the A/F sensor.

 

[BlankWoody]

Would that cause the noise that the exhaust manifold is making?

 

[james'99]

Seems that way. Can you describe the noise more?

 

[BlankWoody]

It just sounds like its stuttering. Like something is in the actual down pipe stuck. It'll go away if i let go of the pedal but as soon as i go uphill or level out and try accelerating the noise comes back.

 

[james'99]

It just sounds like its stuttering. Like something is in the actual down pipe stuck. It'll go away if i let go of the pedal but as soon as i go uphill or level out and try accelerating the noise comes back.

I mean, I suppose that could happen with something stuck. Can you take a video?

 

[BlankWoody]

Video of the noise. Any ideas???

https://vid.me/bqwX

 

[honda_fitted]

It sounds like your down pipe is vibrating on your subframe. Pop the hood and look at the down from the top. If you can have someone rev it, look close to see if it's that