Alright, so i have a 2004 Chevy Duramax with the lb7 motor, and its all stock except for dual FASS fuel pumps, and a 4" turbo back straight exhaust.. when i start my truck and let it idle my trucks turbo makes like a vacuum sound rather than an actual whistle. i dont like the way it sounds and would like to know a way to just have the normal deep rumble sound of any other diesel. thanks.

 

if its all stock why did ya get dual fass pumps? and correct me if im wrong your turbo shouldnt be spoolin if its at an idle. is this when the hood is up and your looking at the motor or standing at the front of the truck? or just in general

 

tuning can change that

 

it doesnt really "spool up" at an idle.. it just has like a sound like its blowing out a lot of air or something. its def not the way it sounds when the actual turbo is spooling up. also i didnt put the fass pumps on there myself the guy that i bought the truck off of is who put them on there.

 

thats the way it sounds normal, like a vacuum cleaner

 

you have an LLY a VGT thats why your getting the "vacuum" noise you describe, the LB7 wont make that sound, it has a fixed vane turbo

My LBZ always makes the whistle when it idles up in the cold, its normal, its also normal if when you truck is idling for the turbo to cycle the vanes, so you will get a quick whistle to a deep rumble and them back to normal