I am running a UPR o/r X, 2 chambered original flows, and 3x22" tips. The catback piping is stock. The upper manifold is stock.
I will be the first one to admit the rasp on the X-pipe at certain times. But down low, it gurgles and sounds soo mean. Half/full throttle in a high gear from ~mid 2's - 3300rpm brings about lots of rasp. Above 3300, it flat out sings, it sounds sooooo good. The rasp at the lower RPM sounds aggressive, it makes it sound really p!ss3d off. In fact, I had a truck the other day who was tailing me, and he finally got up beside me and yelled "your car sounds tight bro!". The rasp at 2200-3300rpm sounds like a dirty scratchy moan, it sounds pretty sweet. Off idle at stoplights, it sounds really echo'ey and mean.
The thing I noticed is that when your cruising at ~2800rpm, and gun it, there will be a metallic rasp at first, but as the RPMs rise, it gradually turns into a roar. The transition of the sound is awesome, it sounds like a beast whaling and moaning and then roaring.
The bottom line is, there are positives and negitives about the sound of an X pipe, IMO. But you gotta take the bad with the good, right? In my opinion, the good of the pipe far outweighs the bad. Maybe my opinion will change down the road, but for now I am loving my setup. Makes my Cobra sound really p!ss3d off.