Hi mate.. the two piece trigger doesn't really turn it into a 2 stage.. It basically means the first part of the travel is against spring pressure and the second part is against the sear which is under the regular spring pressure.
I've changed out the regular one on every Vulcan variant uve had and it improved the trigger no end. The trick is to get a click pen with a pretty tough spring in it or to buy a spring with similar dimension but lesser wire diameter off egay. Youre looking for something just slightly less stiff than the stock one.
Polishing the engaging surfaces of the trigger components as well as the slot in the piston when the main sear goes, really improves things.