I'll give you a tip. Get a small servo extension and remove the red wire. This way you won't have to remove the red wire from the ESC in case you want to use the BEC from the ESC. I used a separate BEC with a Castle ESC a couple of years ago. The separate BEC was also a Castle. I followed their instructions and had no problems. They wanted the red wire out and that's when I used the 3 inch extension.