There was a guy at Dent the other year with exactly the same thing on his XBR. Not sure who made them, probably an 80's accessory when they first came out as I can't ever remember seeing ally s/a's for XBR's advertised. It was a really nicely made piece of kit, looked really trick, but I can't see a lot of point other than looks as there's nothing wrong with the original XBR S/a as far as I know. Maybe the shorten wheelbase would sharpen up the handling a bit?