I test drove a 2008 GMC Sierra Denali this afternoon and was quite impressed. When I turned the key and the motor "started", I felt a very slight torque of the cab upon start up but other than that I had to look down at the tach to actually see the motor idling. I walked around the permimeter of the truck while it warmed up, and could hardly hear it running. If it weren't such a cold day I wouldn't know it was running while out back by the tail pipe. Upon inspection under the hood, all you could hear was a feint ticking of the lifters under the engine covers. I was overwhelmingly taken back this afternoon by how far GM V8 technology has come.

The salesman who rode with me was a pimple-face newbie who couldn't answer a single question of mine if the answer wasn't found on the window sticker. I know GM is crazy about NVH (noise, vibration and harshness) levels (which is a good thing), but does anyone have a clue as to what GM changed from the classic Gen III design to today's?

 

I went and test drove an 07 Escalade for my wife and was shocked at the rumble at idle. I do know that they have cat, muffler, resonator, and 3 1/2 imch exhaust. I was also surprised how strong those motors are

 

oh ya i heard a escalade at the mall yesterday idleing and it def has a rumble to it!!!

 

my '08 from the factory idles loud, as far as the exhaust not is concerned... louder than my '01 did with stock exhaust

 

Why they are Gen IV's now. They changed them to add the AFM and VVT. It was enough of a change to make them another generation. Like the Gen II LT1 etc was different enough from the Gen I SBC.

 

They've always been quiet. My 2000 was so quiet there's a couple times I'd turn the key not realizing the vehicle was already on.

 

my 07 5.3 was louder then my 08 6.0.

 

Both my '99 5.3 and my '08 when stock were as quiet as i could ever ask for. Think the '08 engine is quieter, then again it is new where as the '99 had about 140k miles. Take the mechanical fan off the '99 and run electric and seemed as quiet as the '08.

 

Nothing a cutting torch can't fix.

 

They do not have a DHM cutout!
The GEN IV engines are redesigned in many ways. The location of the knock sensors, and the cam sensor have been changed. Also no more noisy fan clutch to deal with, which gives the engine more power. Step into one of these new engines, especially the new 6.2L in the HD's and you can clearly hear the throaty air sound.