Correct, the cat back will not cause a CEL light. Your 2 rear O2 sensors located within your stock cats are for emissions. When you take off the stock cats and relieve that much back pressure you create 2 things instantly. 1) You increase the velocity of the exhaust, 2) You reduce heat. Now in order for your rear O2 sensors to work properly they need to take a reading within a certain parameter and stay hot. Now back to the velocity aspect. By increasing the exhaust flow your rear O2 sensors will sample too large of a reading. In turn it sends it back to your ECU and reports the problem. Your ECU then trips your CEL light to make you aware of the problem. By relieving the back pressure your EGT (Exhaust Gas Temperature) decreases, hence less heat. By having our U Bend style O2 sensor non fouler you keep the heat up and the reading down.

Now it is extremely effective with high flow cats. Reason being, the cats are not free flowing and they will help produce enough heat as well as restriction. With the Resonated and straight test pipes the non foulers are effective most of the time. However, there is that seldom case where they do not keep the CEL light off. In the event of that, the only way to eliminate the CEL light is the reflash the ECU with a tune, EX: Uprev, Technosquare and Cobb.

So, in short words, your F.I. HFC's should keep the CEL off, in theory, and it is the most probable scenario and with the F.I. RTP's there is a higher probability that the CEL will light up.

To be honest, I like your HFC's better than the other options just because of this. I'm not sure what the HP gains would be from the F.I. HFC's alone compared to Berk or Stillen, but this no-CEL thing is a BIG PLUS for me.. I HATE that CEL with all my heart...

I don't think anyone with HFC's on 370's have had any CEL issues at this point.

Is that using just the Eliminators themselves, or the SS brillo pad sneak?

No pads or scotch Britte, just the non foulers.

Interesante... Gonna have to look into this.

Also, can you comment as why you chose to go with the / \ cannister look as opposed to the = look?
I personally like the / \ look myself. Just trying to see if there's truth/fiction to the reasons as to why = is better...

right, just non-foulers. I'll be putting on my Berk HFC's this weekend and have no worries about CEL's popping up.

/ \ is more of a straight shot for the exhaust
== gives a little more room for ground clearance with the mufflers

unless you are going with a big turbo pushing a lot of boost, I doubt there will be any noticeable difference in performance. :tiphat:

I have had Berk HFC's on for about 2000 miles no codes thrown

I just think the / \ looks better lol. The impact in performance wise I heard from the B*** thread was the / \ design allows for air to come up under the rear bumper creating lift, and the = helped fill this gap. Part 2 of that is that same air is then caught in the bumper and creates resistance.

I guess if your car goes to the track every weekend, maybe something to look into, but if you like me my car sees 6,000 miles a year, then I wouldn't worry about it.

guys I will shead some light on the CEL issue. I have had both Berk and FI HFC's on my G37. The Berk threw a CEL from day one. But others have not throwen them. I have had my FI HFC's on for 10000+km now and just got the CEL. but I am running with out the non-fouler. I called tony and he is shipping me out a set to look after me. But he is busy with all you dudes ordering for the 370Z. so slow it down and let him ship me my non-foulers. lol

This might be a valid concern, but it can be remedied pretty easily by making a cover yourself for the rear center underside. I'm kinda waiting to see what I end up doing for cooling the rear diff first, and then I'll look at any airflow issue there after that.

As said above, I don't think anyone's been getting CELs on the 370 with HFCs, at least not the Berk ones. And you need to stop ordering G37 parts so I can get my exhaust faster :p

As said above, I don't think anyone's been getting CELs on the 370 with HFCs, at least not the Berk ones. And you need to stop ordering G37 parts so I can get my exhaust faster :p[/QUOTE]

LOL...+1