making a slite skipping and hissing sound

[strokedout73]

04 with about 70000 miles

did the bullet proof head gasket and egr kit and seems to have no leaks so far but engine is making a slite skipping sound and a hissing sound. im thinking the hissing sound is due to a crank in the up pipe. the hissing sound is only under load or boost and also has loss of power. the skip is only pretty much at an idle but seems to be fine at a higher rpm.

any ideas?

also installed a new turbo and had the intercooler checked but no problems. up pipe?

[Chango]

You might have a leak in one of the turbo boots, They crack easily on the backside which you cant see without a mirror. That would explain your hissing and loss of power