So last Spring I spent weeks bulletproofing my 2004 with the early build 2003 6.0... Head gaskets, injectors, wiring harnesses, IPR Remote Oil Cooler, IPR remote Coolant filter, and about a hundred other parts trying to address as many issues as possible with this POS 6.0... During the summer, the Turbo started to act up (2nd replacement Turbo after stocker went South years ago), so in the late summer I replaced it with a Garrett Turbo... Almost immediately after installing the Garrett, I noticed a previously unheard Turbo "howl", and exhaust rising up into the engine compartment when the engine was fired up, especially noticeable in the cold... The howl is NOT the typical Turbo whistle that I expect to hear when idling or when making boost... It's an additional sound than what I'm used to hearing... I talked to the company I bought the Turbo from and they said it's possible I blew a seal in the Turbo... I've also read that it's possible that I blew a Y-pipe flex fitting... Question is, what's the best way to diagnose this... It's the dead of winter here in Colorado's High Country and the last thing I want to do is tear the top of that 6.0 all apart again... When I fire up the 6.0 cold, the exhaust appears to be coming from under the Turbo, but it's pretty hard to pin point it to be honest... Any suggestions...? Also, the howl is NOT the sound of the coolant fan coming on, as I've heard that sound for years when the coolant hits ~225 degrees...