Yeah, I just did a bit of Googling on the topic. Looks like you can even squeeze a few more horsepower out of your engine with an X-pipe. It makes sense, too; there'd be less backpressure on the piston that's in the exhaust stroke. X's seem to have more advantages than H's, but both are advantageous. Now that I understand the reasoning behind it, I know what I want to do next. I'll probably figure out where I want the X-pipe placed (methods of determining that aren't hard to find, so I won't dive into it now), and have the shop do that when I ask them to put in new headers. Gotta save up for it, though.

05 WK 5.7L
K&N 57 series CAI