Strange noise after header install

[GoldCartridgeGamer]

I installed Stainless Power 1 7/8 with off road pipes on 9/5/15 with approximately 45k miles. Tuned trans 9/24 then did datalog and MAF adjustment on 10/10. Don't have a wideband yet.

This is two videos of a strange noise I hear once hit anywhere between 60-80 mph. After that can easily hear sound at any speed under load in any gear. Cannot replicate when parked. Noise doesn't appear if car stays cruising around town. Checked last night all of my clamps and nuts. Checked under hood. Cannot find anything. Wondering if it's my lifters.

Video 1 is when I first hit 60-80 mph and the sound starts.



Video 2 is after I ramp off highway and drive around 45-50 mph on street.

[SS Blinder]

did you check tunnel brace and/or heat shields as well?

[GoldCartridgeGamer]

Checked tunnel brace last night as well. I am still on stock L99 exhaust (saving for a catback). Everything appeared fine. The sound doesn't seem to be coming from that area though. Checked heat shields under the hood and nothing looked wrong. Did not check heat shields under the car though.

[Apex Motorsports]

Definitely sounds like something making contact and vibrating together under load. Hard to tell where it is coming from in a video but get under there and look for signs of contact under the car.

[GoldCartridgeGamer]

The sound is coming from the passenger side and before the tunnel brace.

[GMTool]

I'm having a hard time hearing what noise your talking about in the first video. In the second one all I hear is a car that sounds like it's missing, backfiring, or an exhaust leak. How is the car's performance, is there a noticeable lack of performance during the noise?

[GoldCartridgeGamer]

The car's performance is great when I hear that sound.

[GMTool]

I once had a heat shield coming in contact with the drive shaft above and to the rear of the tunnel brace area, the heat shield got moved/bent a little during my exhaust changes. I had to reach up and bend the heat shield away from the drive shaft. You still have the stock catback on so it doesn't seem like this could be it, but you never know.

[GONIF]

Check your motor mounts .

[GoldCartridgeGamer]

Removed tunnel brace and checked heat shields with help of a friend. Still making noise.

[GoldCartridgeGamer]

Motor mounts appear okay.

[Badfinger]

It's hard to tell from the recording but to me it sounds like loose sheet metal or a bolt loose in sheet metal. See if it's motion or wind related. Does it make that noise reving the motor or must it be moving? I had a loose top heat shield on a catalytic converter on an older Caddy make a sound like that.

[GoldCartridgeGamer]

Will be taking exhaust down tomorrow and checking. Does not make the sound in park.

[Cam 427]

The exhaust system will extend some as the temperature of the exhaust climbs. Check your piping for adequate clearance around the transmission cross brace, tunnel, and rear end suspension cradle areas. Also, check clearance of the starter heat shield. I had to bend mine a little.