Two nuts hold each cat pipe to each manifold; some of these nuts are more difficult to access than others. With the nuts removed, the driver and passenger side sections of cat pipe come out individually, each with two cats in it. |  | 
Underhood, the strut tower brace comes off, and the Vortech charge cooler and tubing is moved to provide access to the manifolds. On the passenger side, the coil bracket (including Vortech heat shield) is removed in order to better access the manifold. |
The spark plugs then come out. This passenger side is pretty open and easy to work once the aforementioned bracket and coils are out of the way. The dipstick tube presented an obstacle and had to come out. One 15mm bolt and it's out with a slight tug. |  | 
Six 10mm hex-head bolts hold the exhaust manifold to the cylinder head; the manifold comes out the top. Don't lose the bolts, they will be reused. |
On the driver side, there are a few more obstacles to contend with. First off, the coolant reservoir is in the way. By disconnecting the Vortech bypass valve from the supercharger air inlet duct, as well as the tube leading from the outlet of the supercharger, we were able to temporarily move the coolant reservoir up and forward enough to access the entire exhaust manifold--without even draining a drop of coolant! The driver side coil bracket comes off simply for ease of access to the exhaust manifold. | 
Access on this side is a bit tighter due to GM's poor placement of the computer and its accompanying heat shield (revised, thankfully, for 2005). We opted to make quick work of these manifold bolts with an air-powered socket wrench. This manifold is then removed from the top, just like the passenger side. |  |