Definately a recommended item,
Have the HD on the 04 pumpkin had it on the 05 Cherry and its on the 07 by default. I haven't had any issues with any of them. The whirling is a bit upsetting when you first hear it, but it goes away as a normal sound once you accept it. What I liked is smoother shifts, easier neutrals, and the fact as time wears on I am not having to have a service done just to make sure the primary chain isn't slapping around whether it be a 5k or a 7500 service. Michelle is also happier with it she says its a very noticable improvement.
Would recommend it, provided you install the kit to the letter of what they say. Any deviations = possible / probable issues. In my case I had a countershaft that was coming loose or starting to so while they were in there under warranty I slipped it in for a couple of xtra dollars ya know

-harry