I've had my OBX headers on for about 5-6 years now and the other day I was driving through a lot with insanely high speed humps (ones you go up, drive 20ft, go down) On the way down, something hit. It wasn't the front lip hit, more like a big thump. I was going REALLY slow so I didn't think too much of it. Then the last 2 days I have been getting LOUD resonance at around 2250rpm (loud metalic buzzing).
Ok, so my question is. Could I have hit the headers on the hump and damaged my headers? If I cracked a seal, what would it sound like? In the past 5-6 years that I had them on, I have never heard this sound before, at least not to this level.

 

Sounds like you hit the header. jack it up safely and get under and look for damage

 

I'm going to take a look this weekend, aside from the resonance, is there anything else I should listen for that might indicate I have a leak?

 

Look for black carbon soot on every seams of the header. Exhaust leak will deposit black soot right at the leaking cracks.

 

so lifted up the car this weekend and looked under for any damage. I can clearly see where I hit the speed hump since it left a HUGE yellow scratch under the car....BUT more towards the front and nothing on the headers or exhaust! So my question is....is there a way to reduce the resonance that I'm getting? I realized it's only there in the higher gears. Like if I'm on a highway and going uphill, in 4 or 5 gear it does it, but if I downshit to 3rd, it doesn't make the buzzz.

 

Retorque the header bolts

 

Do you know what the torque should be set at?