You probably won't be able to tell the difference, but it's there. You guys may not work in science, but they do take time to measure stuff like this.
So again, what did they measure?
It may sound unbelievable, but companies often compare/contrast the current design with its predecessor.
Not unbelievable at all. Most companies obviously do that. But they generally do not make claims like the one that "the newer model is 3 percent stiffer" - for good reason, because it makes no sense.