It's not changing the size. I'm pretty sure that's just a visual illusion created by slight differences in angles. Kinda like the arrows thing:
<img src="http://fun.front.lv/i/illusion_some_things_appear_bigger.gif">
And as for the maintaining aspect ratio... why not just add one event?
And yes that example is a little extreme but I did that so you can see the ratio is still as it should be.
Also, any other size differential comes more from the fact that you have a sin behavior changing the size anyways.