Hi,Welcome to the club!
There are 5 different parts you could be looking for. Which cat, and which trim?
Since you said headers, plural, I'm guessing GT (however a lot of people use plural for the single GS header) but need to know for which direction to go. If it's the cats on your manifolds that are bad, headers aren't a bad route to go, but be aware you'll need a tune to get the full impact of them. RRE used to make them, and you can still find them popping up for sale used around here in good condition. If it's OEM, it shouldn't be hard to find, but will be expensive. If it's the 3rd cat, you could cut it right off, if you're comfortable with that, and just replace it with pipe (local laws depending)
If it's a GS and the main cats are bad on the manifold, there is a 4-1 header on eBay, but be warned, it's junk. The welds all need to be redone after a while if they don't leak right away, and the O2 sensor bungs are in the wrong spot so you'll need to weld one into runner #1
Going catless on the manifolds will throw a check engine light. You can hide the symptom often times by using O2 spacers. The best option is a tune that fakes the downstream O2 readings so you have no code triggered or pending for it. The 3rd cat won't affect anything ECU wise. Costs about $350 plus a Tactrix Openport 2.0 cable, which used go for $100 semi-commonly around here
Assosiate00's answer above it exactly what you need to knowHi,
Just read your posted information concerning catalytic converters - Thank You!
I have a 2006 Mitsubishi Eclipse 2.4 L and I did not know that the catalytic converters are located in the manifold.
Are there really 3 catalytic converters in this car? And, is this why when I search for an OEM Converter, I see pictures of the manifold? Please let me know if you have a chance to reply.
Thank you again!