I have a 05 5.3 ECSB. When I step on the gas to go WOT and it shifts gear or if I let off the gas when the RPMs are high. I hear a PSSSST sound almost the sound of a turbo but not as loud. I am thinking header leak so I bought new gaskets going to put them on this next weekend but trying to think what else it could be if it turns out that wasn't it.

 

did you buy the truck used? are there any performance mods done to the truck that you are aware of?

 

It just started like about 2 weeks go but it in 06 stock i have added CAI, headers, predator tune, full SLP exhaust and high flow cats no muffler just resonator have had it this way for a over 5 years did just upgrade the transmission its a 4l60 with better internals and a servo.

 

Could it be the CAI not being connected all the way?

 

most the time a header/manifold leak will cause a tick or tapping noise

 

Hmm I see if I can get some video/audio of it the CAI is connected you hear it right after the shift

 

Yea a video would be good.