if the 400ex is too stiff for you, you must have thought the stock one was locked up ?? or you only weigh 50lbs,
the 400ex is a great, plush shock,
wheres the preload, compression and rebound settings on the 400ex, turn them to the softest setting (S) < on the shock, and back that spring off
its the yfz's that are too stiff, especially without long travel a-arms , which is what they require to run them properly on our bikes