md11plt

All this talk about headers has me wondering if anyone is running CAT bypass pipes. Are there any CEL problems? How about power gains?

Tom

AndyT

i will be running evo dump pipes, no cats, no mufflers no nothing. If you strap the 2nd O2 sensors up in the engin bay where they can read clean air, then there should be no CEL.

viperbob

The system has a learning capability. After resetting the CEL a few times for the O2 issue, it will stay off. First time I did it, it took 2 resets and then never came back nor did it register a code in the ECU. The ECU thinks that the fault it is detecting may not be a fault so it does not check on it anymore. I even noticed if I unplugged my battery, that it did not come on. Then I upgraded to a Protomotive setup and disabled the O2 funtionality for better overall performace.

md11plt

Can the OBD readers that you can get at the auto parts stores reset the codes and CEL or do you need one of the more expensive laptop programs?

Felix

Standard OBD-II sw should do the trick.

ca993twin

md11plt,

Does Utah have emission testing? If so, you may instead want to consider 100 cell race cats and muffler bypasses. This will be fully smog compliant, and will get nearly the same benefits as cat bypass with mufflers. Actually... the 100 cell/muffler bypass system may be lighter and provides better cooling for the turbos. Just another option to consider.

md11plt

No Emissions!!!!!!!!!!!!!

AndyT

who makes 100 cell cats ?

ca993twin

md11plt,
"No Emissions!!!!!!!!!!!!! " You lucky bastid.

AndyT,
"who makes 100 cell cats ?" Try Kevin at UltimateMotorWerks... he makes large diameter (yes, size does matter) 100 cell cats for our cars.

Bradford

Is it possible to just bypass the cat and muffler with a straight pipe as AWE sells and put a small muffler in line? Would there be any benefit by doing this?

Kevin

I wouldn't suggest just taking off the cats and installing bypasses without a ECU modification. In the end it just never works out.. The ECU stores the fault code, the error code is still in the ECU, until cleared, then it will always search for the O2 value differences and the cycle is started all over..

The truth is, you need to Tune for more HP and or larger turbochargers to get the HP and added torque. Installing or taking off the cats won't net you a gain in HP or Torque.. Yes, you free up the turbochargers, but you will notice the car surging and stumbling... This is cause be the richness of fuel that results, without increasing boost and timing its a wasted net effort..