headers..., what will they do for me? Options

[celicaluva79]

Was looking at headers on ebay for my st. Would just headers give me any extra power at all? If so, how much?

[95CelicaST]

Why were you looking at multiple manifolds? The 4-cyl motors only have a single header, not headers.

[Box]

All of the headers for the ST Celica on eBay were actually meant for the Corolla. It'll fit, but you'll have a gap between the down-pipe and the secondary cat(94-95 anyway, not sure about 96+ having a secondary cat). You also have to deal with throwing off your downstream O2 sensor, since there isn't a cat in front of it anymore due to the header. That's if you even weld in a sensor hole for it into the new down-pipe. What I plan on doing is just removing everything past that downstream O2 sensor, secondary cat included, and replace with straight pipe and have a muffler at the end. Some marginal gains, sound being the main reason, and don't have to worry about throwing sensors off. Until they make a header that'll fit into place without having to remove the primary cat, I personally wouldn't bother. Not to mention the upstream O2 sensor only reads off one cylinder with the header, versus all four in the OEM set up. To me it seems to do more harm than good.

[celica74]

All of the headers for the ST Celica on eBay were actually meant for the Corolla. It'll fit, but you'll have a gap between the down-pipe and the secondary cat(94-95 anyway, not sure about 96+ having a secondary cat). You also have to deal with throwing off your downstream O2 sensor, since there isn't a cat in front of it anymore due to the header. That's if you even weld in a sensor hole for it into the new down-pipe. What I plan on doing is just removing everything past that downstream O2 sensor, secondary cat included, and replace with straight pipe and have a muffler at the end. Some marginal gains, sound being the main reason, and don't have to worry about throwing sensors off. Until they make a header that'll fit into place without having to remove the primary cat, I personally wouldn't bother. Not to mention the upstream O2 sensor only reads off one cylinder with the header, versus all four in the OEM set up. To me it seems to do more harm than good.

Had the obx on mine for 3 years now. Did notice more top end pull. It does change the torque curve. Cel didnt come on for 2 years for the seconary o2. Has come on sense i reset it. I had a parts car and just slapped a very very high flow cat from it on to fix the gap. Has worked well. Did have to wrap the section that went over the cross member because it was rattling along with the section towards the rear.yes i know not the best setup but it works just fine. I also cut it at the rear axle. Has a nice tone for what it is.