It's not a big deal to play with the adjustments. If they open too soon... you will have a "Bog" in the middle. (Won't pull as hard to the top) AND.... if they open late.... you will have a hesitation. (The RPM's will hang, and all the sudden, they will jump)
The idea is to make the transition as smooth as possible.
My personal XP has a very "dirt bike" feel to it. It will run a little rough at about half throttle, and at around 5000 RPM.... but as soon as you smack the throttle open... it clears out, and takes off. If I turned the adjusters out a little, I would make the transition smoother, but I would give up the strong mid pull.