The "X" pipe allows the exhaust gases to escape a little faster than the "H" pipe, so if it were mine I would put the "X" pipe on. The "H" pipe is certainly better than two straight pipes, but not quite as good as the X. You will get a tad difference in the drone of the mufflers, and the H will give you a tad deeper drone, but not worth the difference in power. The H pipe gases have to make a sharp turn to pump gases from one pipe into the other, whereas the X is pretty much a straight shot. Go with the X.
BTW, welcome to the site. Pull up a chair