I was down at the drag strip tonight running. I was coming up the return road and i noticed kind of like a exhaust leak noise coming from the driver side of the engine. I got home put it on ramps and crawled underneath the car and looked for any holes in the headers and tightened the clamps, but they were already tight. Only thing i can think of is maybe a broken valve spring, but the car runs fine. You only hear the sound when you give it throttle going up the road, that is what made me thing of it being some kind of exhaust leak. Your suggestions will be appreciated. 01 pontiac firebird A4. Longtube headers texas speed X-pipe

 

well my lifters went last year and it made a noise all the time and got louder as i gave it more gas. So that shouldn't be it. id say pull the valve covers and take a look and see whats going on and take some pictures to share that may help other people help you.

 

Did you try tightening the headers themselves? Could be the header gasket.

 

O.P try and make a video of it so we could listen to it as well that might help others decide on what it is.