Well, I bought these parts back in July but then was in a major car accident and spent 5 weeks in the hospital, now I'm home on recov and am interested in getting my celica finally finished. So I have the header, hi flow cat, performance exhaust muff, and I'm sending my head to get totally rebuilt and ported and polished. What gains and responses can I expect? I also have a injen sri. 96 gt

thanks guys!

5-10whp.
tops.

thanks!

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and probably a CEL and about 10-20% drop in gas mileage

why the CEL? The hi-flow is a "real" legal replacement and the exhaust I have now cause no CEL and the header comes with a O2 bung for the sensor. After a quick tune won't it be fine?

because being obd2 you have a pre-cat and an additional O2 sensor. the sensor that matters though is the very first one. the one after the precat is to monitor for emissions, not for the PCM to use for fuel trims.

what can i do to remedy the cel when it comes up?