To the best of my knolwedge X and R have the exact same exhausts. Have a look under the saddle of your mate's bike see if he's got the snorkle taken out, because normally when the snorkle is removed the bike has a distinct deeper tone.

As for the pipe lenghts, are you sure? Did you use a measuring tape to compare the difference? I ask because I can't see how anyone in their right mind would modify a set of original exhaust by cutting the lenght of these pipes and gain nothing in performance.

Besides the original exhausts, are a be-atch to work with because unlike after market ones, the original are one piece (heavy basteeds) from the end can all the way to the joint with the headers under the sump, whereas after market consist of link pipes and cans separately which then join up with the headers under the sump.

I am really confused about this one, mate!