By the way don't use the paper piece of crap. Go to a dealer and buy the new original and use it. The paper gasket will blowout pretty fast. You will notice also the passenger side header has a rectangular port and the H pipe is round where they meet. It will leak and is a pain. I am going to experimant making a gasket out of Copper. Like the Hi-Po copper ones they sell. I beleive that Magnaflow as far as I know are the only X or H with a rectangular port to match stock header.
If you are doing it yourself do a search on how to install it on here. The passenger side is a bear. Get alot of PB Blaster and spray it down for a few days before. A little tip- take a deep well 3/8 drive socket that fits the passenger nuts (15mm? It has been awhile ) and grind it down about a 1/4" or more. With your long extension, swivel and the "modded" socket it will fit in the space around the Sensor better. By grinding it will be straighter on the nut. You will understand when you get there. Also use a porpane torch and heat up the nuts. This will help to come off easier. I guarantee.