Climbo - shut up, please. It's a worry that you admit to not even trying to tap your full potential.

Basically, we spend all but about 8 hours of our day upright, and even for those 8, we're not bent over (I hope anyway). So flexibility is very important when it comes to applying power while bent over your bike.

Back when I still rode skinny tires, I was taught by a knowledgeable racer to roll my hips forward a bit, and flatten my back. This is much easier to do when you're young and flexible, and made a huge difference is my speed.