I think the only things that can be installed are applications, a9lh, and menuhax.You don't install soundhax, it's just an exploit. People use the word install in the wrong situations all the time. Like CFW for example, it's just files on the SD card, you don't "install" it.
And secondary exploitsI think the only things that can be installed are applications, a9lh, and menuhax.