How much louder do stage 3 cams make your car?

[GodStang]

How do you know this? He states in the vid description on YouTube;

"Stock cam" car has bbk longtubes, high flow h pipe, Borla stingers.
"Comp cam" car has bbk longtubes, off-road hpipe, Borla stingers.

No mention of cats, unless high flow h pipe can be construed to mean that pipe has cats?? I totally agree with you that, "The cats will drastically change the sound/volume."

99% of the time "High Flow" means with cats and "off-road" means no Cats but I guess he could of used the terms interchangeable but the stock does sound catted.