I recently moved into a 2 story house that was built in 98. The problem is that it has really bouncy floors. I removed some sheet rock from underneath for some other project before I deel with the bounce. After removing some sheet rock, I got a look at the floor joist. They are the silent floor system with 2X2 at the end with OSB (I believe) and 12" high. They are spaced 24" and run 13'. The problem is that when it was installed, they made a large hole tthrough it to run the a/c vents. The vents run almost the hole length of the room. Now from my understanding, joist are only as strong as their week points. At the point where the vents run, it looks like they have reduced it to only the 2X2's holding up the upper floor. Does this look strong enough to you guys? Can I or should I try to reinforce it? Sorry if I haven't explained it correctly. I am trying to post pics. I hope it helps.