I have an annoying high pitched hissing coming from engine compartment when accelerating and load on engine, ( no there is no cat or varmints, under hood ha ha ) sound more like a high pitched cricket noise. sound like left side of engine so I think that would eliminate turbo squeal but not positive, I have checked for vacuum leaks, everything that works off vacuum works fine, I put new gaskets on air horn and tightened all connections. one thing is the noise came after I installed ispro electric fp gauge I don't know if that's related or not, no leaks, I have run out things to check, has anyone else had this issue or suggest anything to check, so far the only option is to turn the stereo up so I don't have to listen to it,

 

Intercooler boots ?

 

yeah sounds like boots.

 

X3 for boost leak.

 

I checked the boots, pulled them off and looked, no holes or cracks that I can see and made sure they are clamped on good

 

Intake horn gaskets?

 

somewhere you have a boost leak.

 

intake horn gaskets have been replaced, still leakiing. I put my daughter in the truck with engine running and I got under hood, had her put brake on and in drive and accelerate it, noise sounds like coming from below air horn somewhere but cant pin point it.

 

Just spray some water and see where it blows it out