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CoupeVQ35CVT »
https://forums.nicoclub.com/coupevq35cvt-u137499.html
Tue Jul 21, 2009 7:56 am
Usually you want to retune the ECU after a header install to gain any real #s but I understand you will get some benefits. Be aware it may throw the CEL light due to O2 sensors, depending on how you set it all up. I had my header installed on the Sentra, with a Magnaflow cat after the downpipe. The first 02 sensor was put in the header, and the #2 sensor after the cat. However, 98% of the time the car would still throw the CEL and complain about the sensor voltage.
Go for the header if you are able to deal with the legal smog crap (most new cars don't get inspected for the first two years in Texas).