Highflow Cat

04_yelneon · Post by **04_yelneon** » Sun Oct 28, 2007 12:10 pm

I just got my exhaust done on my sxt. I bought a magnaflow highflow cat from modern performance, an took it down to my local muffler shop to be put on. I didnt notice til i got there, but the 02 bung on my stock cat is in the middle of it and the bung on the new cat is toward the end of it. The guy told me it may throw a code and the engine light may come on. Sure enough it did. My question is, is there way i can get the engine light to go away without getting another cat?

Post by **occasional demons** » Sun Oct 28, 2007 12:37 pm

I'd check to see if the connector for the o2 sensor is plugged in all the way. The cat.s with the sensor in the middle are for ULEV. The sensor is only getting the benefit of the first brick. the ones on the end get the full effect. I would think that being at the end it would have less chance of a cel at the end than in the middle, unless it uses a different 02 sensor. You may have to get a sensor from an older style exhaust or change the cat. (which may be cheaper) But I would check with modern first to see what they say and/or go to magnaflows website to see if there is any info there.

DJ CptnCrnch · Post by **DJ CptnCrnch** » Sun Oct 28, 2007 9:48 pm

did u try to reset the codes...i just installed the same one and dont have any codes...unhook the battery for 15 mins...see if the code comes back

Wenuden · Post by **Wenuden** » Mon Oct 29, 2007 12:47 am

I just replaced my exhaust fron the o2 housing back, and turned the car on for a few seconds with everything off, it set off the check engine light. after i got everything done and the downstream o2 back in the new cat, it took about 20 miles of driving for the cel to go off. i was going to reset the pcm tomorrow if it hadn't. and then replace the sensor if that didn't work.

Powehouse28 · Post by **Powehouse28** » Mon Oct 29, 2007 4:47 am

Just a question isnt it bad to run a high flow cat on our car's i thought that we weren't pushing enough back pressure and would result in a loss of horse instead of a gain?

kevo · Post by **kevo** » Mon Oct 29, 2007 12:32 pm

just use the sparkplug non-fouler trick

http://www.msprotege.com/forum/showthre ... =123634664

I would not recommend the non-fouler trick posted here and on srtforums. It only uses one non-fouler which generally is not enough to trick the O2 sensor.

half_twisted · Post by **half_twisted** » Mon Oct 29, 2007 8:10 pm

Powehouse28 wrote:Just a question isnt it bad to run a high flow cat on our car's i thought that we weren't pushing enough back pressure and would result in a loss of horse instead of a gain?

what about the emmissions inspections done to check the nox level in smog. would we still pass the smog with a high flow cat.

03neonse03 · Post by **03neonse03** » Mon Oct 29, 2007 9:23 pm

i actually used the non fouler trick found here, and am still running it with no problems. so i WOULD recommend it. the only thing i did differently was i didn't drill or anything, just plugged it in as is.

Powehouse28 · Post by **Powehouse28** » Mon Oct 29, 2007 11:41 pm

half_twisted wrote:
Powehouse28 wrote:Just a question isnt it bad to run a high flow cat on our car's i thought that we weren't pushing enough back pressure and would result in a loss of horse instead of a gain?
what about the emmissions inspections done to check the nox level in smog. would we still pass the smog with a high flow cat.

From what i know you'll still pass smog. I've heard that you should run high flow cats on turboed engines because all the backpressure is built up in exhaust manifold before the turbo the turbo actually creates exhaust resistance a.k.a backpressure which also helps with torque often being higher than horse. So i guess i answered my own question. But if any of you guys out there really know on the subject feel free to correct me if i'm wrong.