I think I need a new cat. Hi-flo obviously. I can't afford to do my whole exhaust at the moment. Should I get 2.25? or 2.5" and adapters to make it fit my stock tubing? And do I need an air tube?

You're SC, so you need a 2.5" in and out. I used an autosound, but there'* really no difference between all the major players. You should pay under 100 smacks minus installation.

You don't need the air tube. Our generation is a simple setup. Inlet/outlet, no air pickup, no O2 sensor in position 2.

I found a 2.5 autosound on eBay for fairly cheap. I think I'll get it and a couple adapters to make it fit my stock tubing.

Your stock tubing should be 2.5 as well. You shouldn't need adapters.

Where can I get a cat put on? I don't know any good exhaust shops. Will Midas do it?

If im not mistaken i thought that the stock piping for the supercharged engine was 2 1/4. I could be mistaken. I removed my catalytic converter and the intlet for that is larger than the piping because the piping goes into the catalytic converter for a better seal. Im not 100% sure on this but i think it is 2 1/4 piping. Also when i was getting my donut gasket replaced i asked about upgrading the piping to 2.5 inch and they guy told me that the stock piping on the bonnevilles is very good because it has mandril bends. If he were to bend 2.5 tubing for me he wouldnt' be able to mandril bend the corners and i would get worse flow than with the stock 2 1/4. That was actually really nice to hear. Ohh and the car sounds soo much better now after getting that gasket replaced. Before i thought it was maybe the resonators making a ticking noise but turns out it was a leak. Sounds really smooth now. I have no catatlytic converter and about 4 feet of resonator without the stock resonator and a flowmaster 80 series muffler. I love the sounds now. I have spent soo much on exhasut trying to get it just right. Where i am it is legal to have no catalytic converter. Increased mpg by about 3 without it plus additional power.