Take a piece of larger diameter hose or even a piece of garden hose. Hold one end to your ear and put the other all around the suspected leaks (primary tubes, clamps, etc). This will significantly amplify the sound. If you hear "ticking" you know you have a leak and where it is.

 

https://www.performancetrucks.net/fo...-501283/page3/

This guy had the same problem. But it was more of a loud tick. He pulled the gasket and low and behold look what he found. See post 25 for picture of broken gasket.

In your case it sounds more like an exhaust leak. It maybe at the head, or it maybe down below, it could even possibly a crack in the header.

 

Thanks guys, ill give it a whirl. btw the gaskets i put on were new oem type

 

Don't forget to check the collector as well.

 

Sounds like noise my avalanche makes, coming from my transmission in the torque converter area.