The 02-07 all use the same downpipe/midpipe combo. The motor is different in an 06-07, but that doesn't change the part you can swap with. I would just get the CEL fix which is essentially a resistor to run to the O2 sensor if you're just going to sell it. It's illegal for a dealer or junk yard to sell a used catalytic converter, so you're not going to have any luck finding a used one if not a trade from a private party. Brand new you'll be looking at around $1000 to get a new downpipe and midpipe. Not worth it, in my opinion. That's why the "CEL Fix" is the route I would go when selling it, but everyone else has a point. It's a big deal to me if I see a car that has aftermarket parts with no tune. You might be better off selling it if you can revert it back to stock. Bottom-line is, every car is fixable, but some of us prefer not to fix stuff and will pay more to get it the way we want it (stock) to begin with so we know it's done right.