The a-arms are a love hate thing with the revo, I ran two years with the stock arms on my revo and then had the chance to buy two full sets of rpm arms for $10 heck might aswell take the deal so I bought them. I tried for along time to break the stock ones but never manage to untill one day I hit a boulder in my back yard at wot and broke the mounting ear on the upper and cracked the lower arm. The RPM arms are a little wider then stock so I replaced the fronts with rpms and left the rear alone and then I upgraded to traxxas extended rear a-arms. I have seen other revo's crack a-arms or snap them by clipping a light pole at half throttle, others I have seen get easily 20ft of air and drive away clean. My freinds truck only broke the front a-arms when his radio dyed and his failsafe didn't kick in and it slammed into a dumpster at wot and it snapped both lower arms, I had a extra set of RPM that I sold him for $10 (yea I payed $10 for two sets but I had to make some profit lol) I replaced all the arms just simply because he didn't wanna worry about the rear breaking and having to hassle with them. Last year at one of the monster bashes I got 20ft of air and landed on the right driver side tire and it drove away clean, next I was going to pull a back flip and my throttle servo glitched from the mud and water kick up on the tires and it let off the throttle so I came down on the rear of the truck....I warped my mugen wing mount (yeah mugen one of the top kit companies in the world and MUCH greater quality then hpi).