Hi there sir sam. You said your getting a 400 so is it safe to say you havent gotten it yet? Wait untill you recieve it and after riding it for a bit you would be able to better evaluate if you require an aftermarket windscreen or not. From the posts that I've seen , it seems to me that if your under 6 ft tall than the stock screen seems adequate. If your taller than 6 ft, thats when you start to experience the wind buffetting. Good luck and happy riding!