Anyone knoww where I can get a set of upgraded A-arms for a XXX 4G?

You mean the losi xxx-graphite plus? I used to have one and I never got around to getting a beefy set of front a arms. However the was a company called dpm racing that made a set of machined delrin arms that were said to be indestructable but I could not find any info on them when I googled em anyway that's all I can tell you...good luck bro!