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Advice on cat less headers needed

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Hello all,

First let me apologize for asking a question I'm sure has been asked before, alas I did not find the clarity I was looking for in the forums. I have a 2001 boxster 2.7 that I want to put cat less headers on thus removing the associated o2 sensors. Something that I understand is do-able. I've found posts that the sensors are " deletable" without kicking the cel light. What is meant by deletable?, do I just unhook the bung and tie it back? Do I leave the sensor hooked up and tie it back? I believe I'll have to flash the dme after the change as well. This sounds like it can be done from a laptop with the correct software and cable. Does anyone have experience doing this? What exactly is entailed?


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I think you need to understand the process a bit more, and we would need to know a bit more about where you are and what you are trying to accomplish.

First of all, why do you want to get rid of the cats? If you are just adding headers, you should also recognize that the potential for increased power output via this route is rather limited without going the full "ten-tenths" in retuning the engine, including a DME re-flash with one of the aftermarket programs on one of these engines. As the US versions of the 986 use four O2 sensors (two per bank), while the "ROW" (rest of the world) use only two (one per side), it is possible (using a PSTII or PIWIS) to re-flash the DME to ROW status if you remove one of the sensors from each side to prevent throwing related codes. But in the process, you defeat the DME's ability to alter the fuel trims accurately, which leads to higher levels of pollution. In some states, visual inspection of the emissions systems is part of the annual inspection process, with the cat and O2 sensor missing, which could lead to some major problems. In some states, they still plug the "sniffer" in the tail pipe to test the cars rather than run the OBD II based I/M readiness test; a car with a revamped DME program and missing cats could have problems there as well.

Several header manufacturers also produce good quality headers with the cats and the O2 sensor bungs, so they would be a bolt in swap without all the other associated downsides. And as aftermarket headers add little in the way of absolute performance, you would not be giving up much by having headers with cats.

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Thanks for the reply,I am wanting to eliminate the cats because of a persistent cel light. 0420. I've ohm'ed the wires, changed the 02 sensors and rebuilt the the vacuum switches and tubes, the light remains...my last option seems that either my dme is messed up or the cats are bad. I didn't really want to buy new cats considering the cost so the cat less headers seemed to be a reasonable alternative. The truth is that I don't really care how I solve the issue of the light, I just find it annoying and doesn't seem to effect the performance of the car. The vehicle is my tinker toy, so I like to do the work myself but the knowledge of those that have come before us is greatly appreciated.Thanks

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