The 2007 and later primary doesn't drain as completely or consistently as the older models did, so it's not uncommon to have a problem figuring out how much to actually pour in during a change. The book may say 45 ounces dry, 38 ounces for a drain and fill, but that drain and fill number can vary quite a bit. I always recommend people fill only until the fluid touches the bottom edge of the clutch, with the bike sitting level, and don't try to just measure 38 ounces and dump it in. Even a slightly overfilled primary can cause clutch drag which will affect shifting. I know there are many who just pour in a quart (32 ounces) and call it good, instead of the 38 called for in the book. If you're filling it on a lift or stand that holds the bike upright and level though, there is no need to guess, just fill it to the bottom edge of the clutch and stop.
Jerry