Just did this a few days ago, some quick tips.
-When removing the old pipe, the clamps that hold the stock H to the over-the-axle pipes, loosen the bolts and slide the clamps to the rear, when re installing, simply slide them forward.
-When installing the new H pipe, flip the bolts on the band clamps around. It'll make it easier to get a wrench on it. (you will understand why when you try to get the stock bolts off)
-Install the front portion first, and make sure it is seated before you start tightening the clamps.
-You will have to remove the plastic splash shields in front of the rear tire to get the side pipes mounted.