The slingshot also has more holding power over the Direct drive style.. IF.. it happens to slip you can upgrade the balls to tungsten for more holding power.. But.. that probably wont be necessary, I've yet to have mine slip on me. Also... The under cover slingshot cannot fit through a modded cover. So if your looking for that option go with a standard version or a direct drive style.
The under cover style slingshot replaces the pressure plate. The standard version mounts on top of the pressure plate. You should beable to go back to all stock springs or 3/3 mix depending on your needs.