I'm talking about the torque curve of the XB motor.
Here is Sportrider's dyno of the '04 XB12R.
Unless their bike's exhaust was dented in the same place as the Buell I had, I'll assume it was across all the motors of that year. There is a noticeable lull.
Maybe it's been corrected on the newer models, it pretty much went away with the new exhaust.