Thanks. That was helpful.
Bt when you mean quiet, how quiet lol. As i say this, i understand there is no way you could let me know accurately.

But thanks, i just dont trust youtube sound lol

When you mean quiet, adding rhfc with a 18" cbe will be quieter vs just a 18" cbe ?

no the CBE with any form of a TP, HFC, RHFC will be louder. the cats on a car are super restrictive for sound and flow.

and when I say quiet don't think of it as silent. that's not the case. the addition of a FI CBE and any form of oem cat deletion is a major sound upgrade and volume increase over stock.

also the size of the resonators pretty much only kills the rasp and doesn't hinder the actual exhaust volume that much. 12" vs 18" is just changing the amount of rasp and not really noticeable change in actual overall volume of the exhaust note itself.

Famine, Plague, War, Death, and the horseman they all follow: Capitalism...

Just get the cheapest ones that are resonated. The quality difference is negligible/theoretical as I've yet to hear of one cracking. Worst case scenario, you'll need different bolts. There is some evidence the ART pipes make a few more ponies due to some thoughtfully designed resonators, but they are VERY pricey.

You may need to get multiple de-fouler extenders for the 2ndary O2's or need tuning to keep the ECU happy (the only thing that worked for me). In either case, tuning is advisable without cats.

ART makes more power than other resonated test pipes? Or are the claims that they make more than unresonated?

Also, how many de-foulers did you use? My test pipes have an O2 extension and I just picked up some ~1.5" de-foulers that I haven't installed yet.

Sorry for my ignorance,
What use are these o2 extensions ? The rhfc has an option for extra extensions..do i need them or sometging

The idea is that taking the O2 sensors further away from the exhaust flow will 'skew' the sensor to think that there is more oxygen than there really is. Basically tricking the ECU into not giving a CEL.

But an rhfc is designed in a way that would not happen anyway right ?
What am i missing ?
If i get the rhfc without the extra o2 bungs would i get a cel ?

I have seen a few dynos that suggest the ART pipes make a few more (3-4) whp than regular test pipes -- assuming that isn't just measurement variance, it would have to be due to the specific frequency the resonators have; allegedly they were selected to tune the exhaust pulses in order to improve flow.

That is indeed possible to do, and there is some evidence for it.

Not all resonators will have the same frequency, so no, not all resonators will be tuned (i.e., designed) just right to accomplish that.

However, they are very expensive. If you can find a used set, it might be worth trying out, but expect to pay about double what you would for other TP's, even for used ones...

The primary and secondary O2's are monitored (really, clocked) for voltage changes by the ECU.

If a functioning cat is in place (at least one operating within OEM specs), the flow pulses will slow down as it enters the cat, so there will be some delay in voltage change on the sensors between pre-cat (primary) and post-cat (secondary) on each bank.

However, if the cat is gone, the voltages will change at about the same time. This trips a DTC (CEL) and can cause all sorts of issues with how the car runs.

An extender, or series of extenders (try a single + a L shaped one?), will move the 2ndary O2 further downstream to (hopefully) cause enough of a delay in voltage changes between 1 and 2.

Google spark plug de-fouler and you will find images of it. You can find them at any auto shop or even ebay.

It doesn't always work...

Some folks claim adding steel wool in the bung provides enough filtration to slow down the signal changes.

I suppose another option would be some sort of re-wiring on the secondary O2's to alter the rate of voltage change, but I don't know of anyone who has done that on the Z for whatever reason.

Usually, if the mechanical fix (i.e., adding defouler extenders) won't cut it, the only way around is a tune -- that can shut the monitor system off entirely, and, theoretically, with that off, the ECU doesn't then alter its tune (although I've been told even with the CEL off it might, but I have seen no evidence of the tune solution not working).

NOTE: Even using HFC's will not absolutely guarantee that you won't get a CEL. Remember, the ECU is monitoring rate of voltage change -- if a HFC flows well enough it may make the interval too short and therefore trip a CEL.

FI exhaust guarantee no CEL. if by chance you throw one they will work with you to get it fixed.

I've never heard of a car altering the tune based on the second O2 sensor - it's simply there to check that the cats are doing their job. Am I wrong assuming the Z does this?

I've been told the ECU may adjust the mixture by a good friend who is a very experienced Nissan tuner, but I'm not certain whether it would aim for a leaner burn to reduce emissions or something else entirely.

Next time I talk to him I'll ask.

EDIT: Actually, maybe he was thinking of a different DTC, like for heater circuit (or I misheard him).

Maybe worst issue is the CEL light?

I'm sure on the other comments about why the CEL and how to prevent it, but not on how or if the ECU adjust things in response -- I might just be totally wrong on that point.

If I'm just wrong on the ECU trim response, then that would explain why tripping the DTC isn't that critical -- just annoying.

i thought the same as you jordo, if the cel is on then the car won't be running right.

Nah, I come from the VW/Audi scene where CEL's are always on. Rear O2 does nothing but check O2 levels, it has no influence on how the car runs. As long as that is the only reason your light is on your car will run 100%.

cool, thanks for the input

Right, but how do you know when another CEL is triggered if something else goes wrong down the road? Check for codes daily I guess? :ugh: