At around 60 mph when i hit the gas lightly i get a kind of leaky header gasket noise. I know its not detonation from the chip cause when i just got my intercooler replaced i put the whole truck back to stock and it still made the noise. I asked the service writer to have the mechanic check my spark plugs and i dont think he did cause it stilkl makes the noise. Could it be this loose spark plug noise or whaty is it. Any help would be appreciated

 

Slight tip into throttle and gasket leak noise would suggest loose spark plug, but would happen at any speed. The harder you tip into the throttle the less likely the noise because of pressure on the plug. Noise at only one speed would suggest detonation.

 

Take a good look at the entire exhaust system for leaks. The muffler is known to rot internally (within a few thousand miles) and it leaks exhaust out of the drain hole. Also many trucks leak where the muffler meets the cat pipes. Both of these problems will make what you are hearing.

 

My L does the same thing!!! You can just barely hear it at idle but after it shifts into OD at about 45mph if you let the speed drop a little and then tip in the throttle it is very predominate. I checked the exhaust manifold gaskets and the even took it to a shop to have it put on a rack and checked for leaks. The shop couldn't find anything but the tech did go for a ride and he thought it might be a loose plug and not an exhaust leak. I am going to change the plugs today and see if there is/was one loose.

B