The updated STC is OEM, and the only way to go. I doght you can even get the original anymore. It was replaced with the updated one.

 

Found out where the hissing was from. Broken flex joint on the drivers side U-Pipe. You guys called it again. It doesn't end.

going to replace the y pipe, do an egr delete kit, and rebuild the turbo. I hope that is the end of it for atleast a while. I have only put 2,500 miles on it since buying the truck and I have done nothing but throw money at it.

 

The Hiss you were describing is normaly a Leak I thought it would have been coming from a Joint vs the Flex though. Oh well its good you found it

I also think thats why you overboosted it was trying to adjust for the leak and overboosting

But if you have a bunch of play in the turbine good to rebuild it