The Mexi-Strat I'm playing right now is a bit lighter than my main guitar, an American-made Lone Star Strat, which is still in the shop. I can't figure out why, because I think it's thicker too. As far as I know, there are no hollow sections in either guitar, and both bodies are made of alder. I guess I'll find out someday.
Six months ago, I installed two extra tremolo springs in both guitars to balance the load of the heavy strings I started using. Since then, I hadn't played my Mexi-Strat much until I broke my Lone Star two weeks ago. I noticed an awful resonance every time I played a Bb. It sounded like I was playing a plastic guitar in a bathroom. I first thought it was the natural resonance of the guitar due to its light weight. Soon enough, I inadvertently played with my gut against the tremolo springs through the open back panel, and the noise was gone. The damn springs were singing like demons with every Bb.
So I found a way to dampen the springs. I took a long strip of toilet paper, folded it hot dog style, and used the file that sticks out from my nail clippers to thread it up and down through the springs. It's my latest hotrod custom modification.