solismo...my CEL went off within 2 days of driving with my berk test pipes. tell me ur secret!! i hate staring at that light

It wouldnt be fair for to say yes or no bc I dont know. Do a search under my name and you can have an idea of what my exhaust sounds like with the vid

Well, I'll share my own past experience and allow you all to draw your own conclusions. On my 350, I ran a set of Kinetix resonated test pipes. They did not have the extended O2 port, and they'd throw CELs every 200 miles or so. The remedy was what's known as the 'non-fouler' or 'anti-fouler' method, where you take two anti-foulers and drill one out so that the other one fits into it. What you do is screw one end into the O2 sensor port, and then screw the O2 sensor into the other anti-fouler. Now, the anti-fouler you're screwing the O2 sensor is not the one directly connected the port. You're screwing the O2 sensor into an anti-fouler that is screwed into another anti-fouler, which is screwed into the port. The anti-fouler that you're connecting into, then, is 'nested' into the other anti-fouler, so it's protected from the actual exhaust gasses. Net result -- no more CELs. By welding an extended O2 sensor port right onto the HFCs, Berk is trying to make our lives easier by replicating this anti-fouler method without us having to manually go buy the anti-foulers, drill one out, etc. Now, I'm not 100% sure on this, but I think they may be missing the 'nesting' part of it. In other words, the O2 sensors are being situated back away from the direct line of exhaust gas, but I can't remember if the end of that extended port is actually blocked off or not. If it isn't, then gasses aren't actually being completely blocked off from the O2 sensors. So that would explain why some people are still seeing CELs. If it is blocked off, then it's properly replicating the non-fouler method.

Here's a DIY link to the non-fouler method:

Stop CEL With Test Pipes - Nissan 350Z & 370Z Wiki

I did the same with my 350z when I added a set of Fast Intentions testpipes. It worked just fine. It was a cheap and easy fix.

But for some reason when we installed a set of Helix v2 testpipes on my friend's 350z it didn't seem to work that well. The helix testpipes he had came with the built-in extensions for the o2 sensors, they kept throwing a code for some reason.

I never did like those kind of test pipes, I prefer the ones without the o2 sensor extensions.

On these Helix test pipes, do you by chance remember whether or not the extensions were closed off at the end where they connected into the test pipes? I think that might be the key.

I know exactly what you're talking about with the 'nested' anti-foulers.

The helix ones weren't closed at all, it's just an extension with threads. I wanted to try adding the non-drilled anti-fouler onto the extensions but the o2 sensor wouldn't fit on. For sh*ts & giggles we tried the drilled out o2 anti-fouler, but that did nothing. One other thing I didn't like about the helix v2's is that the o2 sensor extensions are angled down slightly, maybe 5 to 10 degrees from what I remember.

I just read on another thread that BERK is about to design their own cat-back exhaust. I guess I'll be waiting just a bit longer to see how that comes out. If it fairs nearly as well as the Stillen exhaust, I may be going the BERK route for exhaust (I don't plan on doing headers in either case).

Guys, make note the Stillen ones do NOT have Non-foulers and the HR requires them. You will have to get non-foulers added to them to prevent the engine light from coming on due to PO420 AND PO430 codes. If those don't help which sometimes happens, you can get some SS wool and stick it in the non-foulers to help. Berk took this into their design when they developed theirs. Plus they also have the extra bungs for meters if you wish to add one later.

Just to mention here that I have had my experience with Stillen products in the past and have bought stuff from them since 1995. On the other hand I have recently went with Berk on my HFCs because they have a good history of great customer service! And I have to agree here their customer service is great! Stillen though if you have warranty issues, they try to blame it on other things like your car, and will try to find a way to not warranty the product.

That is all I will say. You guys make the decision.

Put SS Wool in the non-fouler holes and then put your O2s back in and this will resolve the issue. Brilo will also work.

Berk will send it for free if you call them. (Great customer service!)

This will happen with all HFCs as the O2s on the HR motors are more sensitive. Depends on the engine and time as mine didn't do it for 3000 miles and it popped on one day and kept coming on till I had to put the SS Wool in.

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.