We recently purchased a box of snack bags (Doritos, Fritos, etc) and although it's hardly scientific the Doritos chips themselves are - to me - demonstrably smaller in thickness. i.e. more thin and brittle, they barely crunch (the dusty addictive nacho flavour is still there :) ....).

So perhaps they're adding more chips but net weight doesn't increase at all? I'd be more willing to measure them if the chips themselves weren't so immediately not-worth-eating anymore.