When I first started running my SC10, I put RPM arms, bumper/skid, and ball cups on it. Mostly because I sucked at landing the downside. Sucked at landing all together. Heard the rumors about the broken chassis. Saw pictures of them broken. So I just ran RPM. About a year and a half later I decided it was time to run the stock parts. The RPM bumper bottoms out more and I hated the look. Well, since switching back to stock 6 months ago I broke my first arm last night. I believe I stress fractured it at Cactus Classic and I finally finished it off. Anyone who saw the front quad at Cactus knows what I'm talkin about and I'm not suprised. The stock parts are better than fine if you can drive decent. I still use the RPM ball cups and they ARE better than stock. I'm happier with my sc with the stock parts.