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.