This is kinda hard to explain, so bear wit me. Ok, when I crank the truck, about 5 seconds then it gets really deep and then it makes this hissing noise for about 2 seconds and then its fine.
I have 5" Magnaflow w/o a cat, and Fingerstick and blocked. Its not that big of a deal, just curious.

Mine does that too, revs don't change, seems like the flow exhaust is somehow changing thru the pipe. Could a blocked EGR hav anything to do with it.

Not real worried about it, just curious. Only happened after the exhaust was put on.

It is normal! The VVT (variable vane turbo) has vanes that are controlled by ECM programming. The sound you hear is with the vanes in the open position when you start it, then closing fully, and back to about half open or where ever the programming is commanding depending on ECT, RPM, MAF, ect. The cycle described is for callibration of vane position on every startup. Hope that makes sense!

This is kinda hard to explain, so bear wit me. Ok, when I crank the truck, about 5 seconds then it gets really deep and then it makes this hissing noise for about 2 seconds and then its fine.
I have 5" Magnaflow w/o a cat, and Fingerstick and blocked. Its not that big of a deal, just curious.


Vane position relearn. This happens everytime you start the truck.

Sounds good to me. Thanks ya'll!:D

Thanks fellas

dane