I agree with Latch, the HS-81's would be better with the 400X. Make sure you set the elevons up like the directions say. I thought mine was on the heavy side so my gas powered mind said add some up. Needless to say it didn't work out for the glide throw. I turned them back down to where they were suppose to be and it flies like a dream now.
I'm using the Futaba 8 rx in mine. If you are considering the 555 look into the Electron 6 instead. It's a Hitec rx but smaller and cheaper then the 555. It's a great little rx, dual conversion also.
Look at the build link on clubzagi.com, they put a lot of good stuff on there to help you out. I called it up and went step for step when I put mine togethor, took me five hours to complete.
