I think you'll be happy with the results. I will add that when I switched over to this setup, it took me like five tries to get the main jet right. I started at 220s and worked down. When I got down to 190s and it still fell flat on its face at WOT, I figured that the mod was not for me and my bike, and went back to the stock setup. I ended up talking to Dave hisself and he told me to go ahead and go down to 180s. It just seemed so lean, I was new to it all, and I was afraid to blow it up. Well, I swapped everything back with 180s and whoopeeeeeee, the first time I whacked it in first, I almost flipped the thing backwards. I had been so close but didn't realize it. When you run this setup, you end up with a smaller main than with the bleed type needle jet. Yours being a 400, you'll probably end up with a little bit bigger main than I did, but it might surprise you. Let us know how it turns out.
I wouldn't bring her home to Mama, but Mama ain't home tonight.