Hmmm it's a strong XBR indeed that "pulls all the way to 100mph", yes, they'll mostly do that, but hardly with much enthusiasm(!)
Popping and banging on the overrun is normally either a loud exhaust, a small air leak in the exhaust or very occaisionally an engine running lean, hardly a major cause for worry imho.
Some XBR's will stall unexpectedly, in my experience it means the tappets have been set to the original factory settings, I can't remember the later settings but I'm sure someone will be along with them... it cured mine completely after I reset them

Good luck! (and don't worry

)
Smudge