Hideeho
These are the mods I would recomend in order of importance to me.

practice time

correct tires for your track

balast weight to balance car & help setup

Avid steering blocks (or at least glued factory saver)

carbon c-hubs w/ shaved u-brace

bb shocks (will be available oct 1) not sure about the springs yet as the AE springs aren't out yet, but I'm betting Avids will be the ones to have

slipper upgrade Avid triad>rcshox garodisk>AE VTS>stock

There are a million other little mods you can do. some will help a little (TiNi ball studs), some just look cool (anodize the Ti turnbuckles), some will help a lot but are expensive (full ti screws, shock mounts, front axles, & hinge pins).

One other mod you will hear a lot about is converting to hexes. Personally I do not consider that a vital mod at all. Doing this mod is a convenience thing only. IT DOES NOTHING TO IMPROVE PERFORMANCE. As a matter of fact, it increases the unsprung weight & rotating mass of the wheel. Both of those things are actually going to hinder performance of the buggy. It is a VERY SMALL change, probably not noticable to 99.9% of the drives out there, but personally I know its there & can't justify spending $$$ on a mod that will actually reduce the performance of my buggy, regardless how little that reduction is.

After all that, I would also say only #1 & #2 are required to win with this buggy.