They will guaranteed.

Ok... are you saying that based on experience with a 350z or this car ?

Josh, this would be a good place for you to step in and comment ;)

Good looking on out on that wool trick, and yes Berk has been fixing their CEL problem, but like I said im not leaning towards any of the two. I just hope BERK would make some headers for our cars:stirthepot:

FWIW, I've had zero CELs on my Berk HFCs, and they've been on the car now for about 1,400 miles. Those miles include a wide variety of driving styles as well as several OBD-II driving cycles (my little OBD-II unit shows me driving cycle progress). Obviously in the pictures we have, the Stillen unit doesn't have an extended tube for the O2 like the Berk one does, but I don't know what that really means in terms of results until we get some people independently testing them.

In all this discussion about CELs and extended tubes, etc., I think we've glossed over something else that's kinda significant. Stillen claims less of a gain on their HFCs than Berk. Although I must say, their web page for the HFCs is a tad confusing right now, because they claim only +9hp and +8ft/lbs tq. Yet, when you open up their dyno chart (for a G37), it shows +16hp and +13ft/lbs tq. In any case, they're claiming less gain than Berk either way you look at it.

350Z with the HR. The HR is so similar to your 370z VHR that it will happen. Reason why Berk said it too that it needs the non-foulers.

Just give it time. Many didn't have the light show for thousands of miles. Mine showed after 3000 miles. Dunno what changed but it did.

It is possible they are using a less flowing cats on theirs compared to Berk, so they may clean better but also flow slightly better. Berks are proven and flow great. If someone get's these cats, please take a picture inside of the cat so we can see how they are made through one of the pipe openings.

What was the actual cause of your CEL that showed up 3k miles after the install though? Lots of things can cause P0420/P0430. Are you saying that you're really putting out too much emissions to the sensor, but it took 3k miles for the ECU to notice? I think that's unlikely. The 1,400 I've got on this setup now are more than enough for an OBD-II drive cycles to have picked up any real problem. What happened during those 3k miles? Other change to the car? Some kind of buildup in the cats or on the sensor itself? Heat changes?

The cats caused it. Exactly as you said. As many have noticed on the forum, it took their cars 3-4k of miles to have a light come on. Some came on right away, but most took a few thousand miles.

Nothing changed on my car during that time. Nothing.

My car should be delivered in about 2 weeks. I was thinking of putting on the Stillen Catback along with the Stillen G3 CAI's. I'm looking more for sound versus a bump in performance (although that's great too). Is adding the Berk HFC's really needed or will the Catback itself do a nice job in getting better sound? thanks!

The catback itself will give you a much deeper sound.

Gahhh I want the Stillen pipes already!

hmmm CEL's with HFC's? tsk tsk. i hate it when i see that light. i had that on my old b13. hmm did anyone have CEL's on their Stillen Cat back alone? or even with the g3's? i really would like to know cuz i'm really interested in getting the Stillen exhaust system with the g3 intakes. i was wondering if they'll throw CELs. looking forward to answers.

I haven't had a single CEL, and I have all three components installed.

^^ Like I said, give it more time. We all thought the same at first.

^^ I'm just answering the guy's question, not taking a position as to whether or not it'll ever happen. And quite frankly, I don't care if it does. If it throws a CEL, then I'll fix it. I just don't consider it that big a deal. If you're into modding, it just comes with the territory as far as I'm concerned. I expect problems, and when I don't experience them I consider it a bonus that exceeds my expectations. IMHO, anyone who expects everything to be smooth sailing just isn't experienced at modding.

I have the Stillen cat back and gen 3 air intake. NO CELS.

Hey Guys,

Sorry that we haven't jumped in here yet. Josh and I hadn't seen this thread until it was brought to my attention.

It's pretty much a gaurantee that the hi-flow cats will set off check engine lights. We are currently working on a way to defeat that though and hope to have that solution soon. Our engineers are testing two different ways to fix the CEL issue. We would like to stay away from tricking the ECU if possible.

In regards to the advertised horsepower output. You are correct, we have a typo on the website and we will correct that ASAP. The dyno for the G37 is the one we should be using for the 370Z but our literature is from the 350Z.

How exactly do you intend to fix it? I ordered the Berk cats, and like you, i'm not too concerned about a CEL. But if it shows up, is the fix something as simple as removing the cat, and then inspecting it and cleaning it out?

Forgive me if this is incorrect, but could the CEL be showing up on these Berk cats because of carbon build-up in that O2 sensor extender tube? could it be something as simple as removing the O2 sensor and then cleaning any carbon build-up? Again, I have no idea, just throwing out some possibilities on what could be causing it.

Dude, review the thread. I already explained the fix a couple of pages back. I even included a link to a DIY with pics.

Edit: Here's the link to the exact post. It's called the non-fouler method. You can also just stuff some steel wool into the port and apparently that works as well. Hope this helps! (Actually, I hope your HFCs never throw a CEL to require one of these fixes to begin with!) http://www.the370z.com/intake-exhaus...html#post55946

Ahhhh woops, my bad. Thanks again, great info on this thread :tup: I hope you never throw any as well, but aparantly you know how to fix em in case they do!

You said you ordered them, right? As in...you haven't installed them yet? If you haven't installed them yet, then you might want to go ahead and stuff some stainless steel wool into those ports right from the get-go, prior to installing. Then you're covered for sure and don't have to worry about getting a CEL in the future. That's what I'd have done had it occurred to me before I installed them.

Yeah, they're currently on backorder, but when they come in, that's a good idea. I'm assuming there's some kind of small screen or catch inside the port so the steel wool won't slip out of the port and into the rest of the cat?

Also, any idea what kind of steel wool? Just any stainless steel wool from Home Depot would work?

No you have to get super uber special stainless steel wool. Only pure stainlessanium steel nitrate with mega ferro-magnetic qualities will help in the atomization of the A and P particles within the C02 condensation patterns. Without it, not only will you void your warranty, but you will also turn air passing through the exhaust into prancing miniature unicorns. Unicorns = rice.

Yes...normal SS wool from home depot...

I believe so, yes. But I've never actually done this myself. I've only done the non-foulers. The steel wool suggestion came from NIZMOZ a few pages back, so he'd be a better person to ask:

LOL. You are such a smarta$$. :stfu: :rofl2:


In all seriousness though, RCZ do you know if there's any chance of the steel wool becoming dislodged and falling into the exhaust?

Haha, awesome, thanks for the input guys. Just added +Rep for the three of you (RCZ, semtex & NismoZ)

Axio, I was just looking at a photo of the HFCs. That extension tube is actually pretty small/thin. If you stuff a small wad of SS wool in there, I doubt it's going to go anywhere. There just isn't enough space for it to move around. What I'd do is stuff the wool in just a little, then allow the O2 sensor to push it the rest of the way in as it's being tightened (vs. pushing it in with your finger or a screwdriver).

aww you missed the unicorns part.

I would assume that is a possibility. I assume the non-foulers purpose is to take the sensor out of the direct flow of the exhaust gas, which would cause it to miss read and trigger the cel? I am not sure about this, I have always just assumed this was the reasoning. I also assume the steel wool is there to create even more of a barrier (yet allow it to pass enough gas through to the sensor) while not melting under the high temperatures of the exhaust gas.

Right?

This is the reason why Berk and others have decided to create out-of-flow adapters for the o2 sensors (built in non-foulers). This is the reason why I am assuming Stillen's HFC will have this feature as well, perhaps evolved in one way or another to keep it from affecting flow.


Careful with the O2 sensor Semtex, it is very easy to damage them, they are sensitive.

Stillen's HFC doesn't have this feature. Have you seen them yet? They're up on their website with pics. Available for sale. That's how this whole side-discussion got started -- I pointed out the lack of this 'feature' on the Stillen HFCs, which means they'll need anti-foulers. Some folks chimed in and said that even with Berk's built-in extensions, you still might get CELs, hence the steel wool.

RCZ, correct. Non-foulers are there exactly as you said, to move the sensor out of the flow to prevent them from triggering a light. Some cars are more sensitive than others and it will trip faster. So the SS wool comes in handy in that case.

Hence my comment semtex.

And expensive.

Apparently O2 sensors are female!

Does anyone see anything possibly catastrophic about making my own o2 fix?

I think any one of these HFC's or race pipes can be made to work just as long as we keep the o2 sensor from seeing turbulence.

Not sure what you have in mind. Just use the anti-fouler method if you're planning to use HFCs or test pipes without an integrated extension tube. That's essentially what the anti-fouler method is -- a way to keep the O2 sensors from turbulence.

I like GTM's design with their cats....

Not too familiar with the exhaust system setup on the 370z. Are these the secondary (main) cats following a pre-cat in the exhaust manifold? Most systems I've seen on other cars have a primary o2 sensor before the first cat to monitor A/F, and a second between the two cats to make sure it is doin its job. There is usually no monitoring further downstream of the second o2 sensor (i.e. in theory, the car would not even know if the secondary converters were removed). Is this not the case for the new z?

Not sure this really matters for those that are planning on heavily modding their cars, but i was thinking of getting the stillen HFC's and the thing that turned me off about the stillens was the fact that they are not CARB legal. so i think i will stick with the Berk's. also apologize if this was mentioned earlier.