Jompa, If you're installling a 500, I'm assuming that you plan on going a bit fast somewhere down the line. The KDX is NOT designed to go fast --It's the master at going slowly over the nastiest of terrain, but try going fast and it will have you on your @$$ before you can say the word. See the frequent threads -- "my KDX front end washes out" on this forum. Use the KX frame. Frame, shock, forks are all stronger to take the extra forces.