The non-foulers push the O2 sensor back a little bit. Basically, when you switch from the stock cat to the HFC, there is a lot more airflow which can throw a check engine code. By pushing the sensor back a little, it will help to not throw it off.

 

cool how much are they and where can u get em from?

 

your local infiniti shop might have them mine did. you could call tony at fastintentions he has some forsale

 

As I recall, BERK recesses the O2 port on their HFCs to address this issue. I've never thrown a light on mine. I'm very satisfied with the BERKS.

 

I threw them from day one with my berks. Took 10000km to throw it with my Fi. but i had no non-foulers. non-foulers installed now and time will tell if i thow a CEL. not really worried if i do.

 

So what is the diff between metallic and ceramic cats?

 

I think they changed the design after so many CEL problems when they first came out.

 

I have Berk HFC's but wanna change to resonated TP's.