As previously reported, my entire exhaust system was stolen a few weeks ago (don't ask, but if you are really curious see http://www.m5board.com/vbulletin/showthread.php?t=112481
). Since I really liked the SS Race mufflers, I went that route again. Fortunately, Will Turner had a customer who wanted to sell a used setup, this one with an x-pipe. I jumped at it and installed it last week. My impressions are that (1) the x-pipe adds little in volume, maybe 10-15%, and (2) the biggest difference is in the downshift throttle blips, which are epic now. If you like the SS Race sound, you will like the addition of the x-pipe, but the difference is not huge.