I want to run duals on My CC also. What I plan to do is ditch the stock compressor all together and buy a aftermarket one and put it where the 3rd seat would be when i remove it. Then I will install rear helper air bags and will retain the auto level system if I can.
If you want to run duals I have heard that you need to get a 94-96 Wagon gas tank. The gas tank on 94-96 wagons is 1 gallon smaller than 91-93 tanks becasuse the left side of the tank is reduced to fit the heat shield and the muffler on that side. You might be able to still route the pipe. There might some people who have did this. Mabey it will work.
You gotta find a new one or buy a new one from GM. Hopfully a new tank wont be alot. I plan on going that method.
BTW Wagon exhaust pipes are routed different than Sedan pipes. The pipes on the wagon are the same as the sedan up to the rear end. After that you need to do some custom work to get the piped over the rear end and to the far sides of the body.
Look under the wagon. You will noticed that the crossmember is bent for the pipe on the right but the left side is straight across.
On my wagon I can see the bolts for the exhaust brackets there on the left side. I assume you can buy OEM hangers from a dealer.
Now. If I only had time to do all this.
In the summer when im back from school there will be alot of work to do!!!