I upgraded the servo saver, but only used the arm the connects to the steering servo (top left one). Its not lighter and the only reason was the origional plastic one didn't stay fixed when tightening the servo saver spring.
I changed to the 3racing center bulk head, it's pretty nice.
About the front droop screws, the front case has bent where the screws srew in, no more droop settings for me.
i think the Alu Rear arm mounts is a good option too, I've broken 3 of those (bad bearing had me crashing often- good excuse huh?
Center CVDs isn't a good option, the pins have broken several times, I like to use brakes.
37t ring gears, way good up-grade, very happy w/ it, run the smaller pinions on small tracks and still hangs in there.
Brake upgrade is also very good. don't remember the model number, but even though it's a couple of bucks, brakes are awsome.