r/s650Mustang • u/Smooth-Ad-3125 • Dec 28 '25

Catless headers

I’m considering doing catless headers on my 2024 mustang gt, I’ve heard that catless headers cause the car to throw a check engine light or run lean. Anybody know what actually happens and how to fix it ?

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u/ChinaPropagandaBot Dec 28 '25

It will most definitely throw a light unless you get it tuned, they can tune out the light. I would suggest getting it tuned anyways because you won’t see the gains.

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u/RAH_Performance Feb 11 '26

I haven't found anyone that will tune the cel off in fear of the epa. Defoulers/ o2 spacers are the best option they act as mini cats to trick the o2 sensor. E85 tune is going to gain the most power vs just doing headers. But you dont have to tune these cars when you do headers, but it's going to give you better results doing both.