The item circled in red is your vac tree. If you see the red arrow pointing at the vacuum line, this is the one I want you to trace. This should go inside of your firewall. Its used for your HVAC system.

Another way to determine if its this line is, with engine off, disconnect that line, have someone start car and listen for the hiss again. If the hiss goes away, you found the correct line. Now you have to trace it.

https://www.gmforum.com/attachment.p...ine=1333652064

Well I will disconnect it to check but if it is the problem I'm driving it over to the mechanics as I'm not fixing it if he broke it

okay so you know that line you told me about it runs along the firewall, around the passenger strut tower, then down behind the battery, then into wire look, and it all looked fine. i pushed a few connection together better around the supercharger snout and followed them to wherever they went i checked every vac line i could find. i also noticed that hissing sound i heard isnt coming from fire wall i think its just the vac tree im hearing lightly. so im at a loss?

Then I suggest you take it back to the shop that did the work. Tell them that you hear a vacuum leak but can't locate it. The labor is supposed to be warrantied.

Yeah I have a appointment for Tuesday to take it back already

Dang, that's 4 days away.

He's not open on weekends and my days off are Tuesday and wednesday

Egr heat shield was on the throttle cable limiting it to 60% lol

But that doesn't explain the hissing you hear.

I'm a retard i was listening to a cold engine i think it was just the iac lol