glasspacks on LSx motors?

All of the newer generation V-8 vehicles- Mustang/Vette/Camaro/ Truck, will have that sound IMO. I know what you're talking about, and it's because the camshaft technology.

Look at the cams specs-- a wide LSA allows you to run longer duration #'s and higher static compression ratios without pre-detonation or vacuum loss. They all do it.

But it's kinda like retarding the timing on your old SBC- it has that weird monotone idle.