Iv notice over the past year of owning my 09 5.3l 6l80e gmc ccsb 4x4 that compaired to my last 05 gmc 5.3l the exaust on my 09 is more loud stock to stock when at take of or low speed in a parking lot. Sometimes it drones at crusing speeds it sounds like it has a flowmaster on it even though its stock I was woundfering why this is . I dont mind though love the throughty sound for stock. Also when in tow haul mode the engine stays in 4 cyle mode longer even if i give it some gas to a certin point. Enyway thats my questions thanks.

 

My 2010 does a little droning too with the DOD disabled....its just plain annoying with DOD on.

Right around 1200-1500rpm and light load...Never really thought much of it until you brought it up. Must be something different in there, likely on the intake side...different ports in the heads, bigger T/B on this one.

 

Or..... the exhaust is different.....

The higher compression also creates more of a growl.

 

It looks very similar to an NBS from 03-07 IMO. Maybe the muffler is different.
I don't know for sure...just what I can eyeball.

I know the T/B is bigger and the heads and intake are running square ports instead of cathedral ports. Valves may be bigger...like you said...higher C/R...Its a very different engine from the last gen.

 

its because the exhaust is tunned to be droneless with the DOD on

even the new hoe's and yukons have better sound than the pickups

 

Only the new 6.0 and 6.2 trucks have the rectangular intake runner. Everything else is still cathedral port.

Other then the DOD drone I'm not sure I know what you guys are hearing. To me it sounds about the same as all the other 5.3s before it, and before I installed the muffler it was quieter then previous trucks because it has 3 cats vs 2.

 

thanks for the tips sounds like dod and head stuff compression must have somethging to do with it.