Test Pipe or HFC?

OMGiGOTaZ · 08-31-2012, 11:19 PM

Well, work kept me from getting to the shop so hoping I can get some mods before the Nopi run so i'm not feeling so Stock and caught with my pants

Ronin06 · 06-15-2014, 11:42 AM

I know this is an older thread, but seems like some disinformation.

1) CEL thrown due to a change in CAT will be because the ECU has found the amount of pollutants is out of param and cannot correct the A/F ratio enough to bring it back in line. The easiest solution and recommended is to tune the vehicle. Simply deleting the sensor will likely leave the ECU in the last known state of the A/F ratio.

2) Test pipes will throw a CEL on a stock ECU. Your choice is to live with it, periodically reset it or delete the sensor through a program like Uprev.

3) HFC due to their construction will be more expensive and theoretically will pass emissions testing and not throw a CEL. In practice YMMV.

4) Free flowing exhaust will produce more HP on the top and mid range. Some engines may see a decrease in low end torque. IMO I would rather have the free flowing exhaust and take the increase in HP.

5) Changes in the exhaust system will result in sound changes. Some good, some bad depending upon your taste. Personally I can live with a little more sound outside the vehicle, but would not want increase in drone. Would also want to carry on a normal conversation inside the vehicle. My goal is increased HP with moderate increase in sound.

08-31-2012, 11:19 PM	#1 (permalink)
OMGiGOTaZ Enthusiast Member Join Date: Jul 2012 Location: Florida Posts: 316 Drives: 12 370Z Auto Sport Rep Power: 13	Well, work kept me from getting to the shop so hoping I can get some mods before the Nopi run so i'm not feeling so Stock and caught with my pants __________________ all you gotta do is...

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06-15-2014, 11:42 AM	#2 (permalink)
Ronin06 Base Member Join Date: Mar 2014 Location: Urbandale, Iowa Posts: 87 Drives: 14 silver sport 370Z Rep Power: 12	I know this is an older thread, but seems like some disinformation. 1) CEL thrown due to a change in CAT will be because the ECU has found the amount of pollutants is out of param and cannot correct the A/F ratio enough to bring it back in line. The easiest solution and recommended is to tune the vehicle. Simply deleting the sensor will likely leave the ECU in the last known state of the A/F ratio. 2) Test pipes will throw a CEL on a stock ECU. Your choice is to live with it, periodically reset it or delete the sensor through a program like Uprev. 3) HFC due to their construction will be more expensive and theoretically will pass emissions testing and not throw a CEL. In practice YMMV. 4) Free flowing exhaust will produce more HP on the top and mid range. Some engines may see a decrease in low end torque. IMO I would rather have the free flowing exhaust and take the increase in HP. 5) Changes in the exhaust system will result in sound changes. Some good, some bad depending upon your taste. Personally I can live with a little more sound outside the vehicle, but would not want increase in drone. Would also want to carry on a normal conversation inside the vehicle. My goal is increased HP with moderate increase in sound.