So you removed the weight, then put the weight back in and wondered why you can't feel any difference?!
Yes, I can feel a 10.5kg loss from over the rear axle, but then I can feel a couple of psi drop in a tyre. The spare wheel weighs 12kg in my MR2, and I can feel a massive difference when that's out.
If Johnny Drive-Softly did it and only ever pootled around, he'd probably not notice. If Larry Track-Day-Hero did it, I'd be amazed if he couldn't.