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Decats...


Adriank

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I'm tempoted to go with a set of these, mainly for the noise aspect...

 

Lots of different makes, APS, Kinetix, Envy own + many more, are they all much the same?

 

Also does anyone know how many sensor holes they should have so you can refit the std sensors back in? I dont want to have to muck about with any CEL issues!

 

Thanks in advance.

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They will have one sensor hole on each cat. Different cats will produce different sounds so probably best to see what people have. I have Magnaflow cats and it creates quite a raspy noise where as I know others make a lower gruntier noise.

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You are aware that you'll lose a fair bit of torque with decat pipes I presume? Assuming that, whatever pipes you get you'll want them to have built-in spacers ideally, to lift the O2 sensors slightly out of the gas flow which should fool the ECU into thinking that you've still got cats fitted.

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You are aware that you'll lose a fair bit of torque with decat pipes I presume?

Yup, I told him that loads of times :yawn: He just wants more noise!

 

Ad: Went back to TGM today and Tom rebled the brakes. Got a bit of air out of it and now I've reset the brake pedal position (was out of spec according to service manual), brakes are all good :thumbs: Also told him you'd be after de-cats soon!

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I haven't decided stew tbh.

 

I've been looking at decats, resonated decats and sports cats, but its a minefield to know what the actual difference will be between them all, in terms of sound and performance.

 

My 5Zigen has a fairly small bore, so im thinking that even with decats i might not get the usual torque loss?

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Honestly, most OEM cats nowadays are nowhere near as restrictive as they used to be (400cell?) so even dropping down to a 200cell cat isn't going to make a huge amount of difference if you're N/A. If you've got some kind of forced induction then it will make a fair amount of difference between having a cat and a decat pipe, but if you just want more noise then it's too big a price to pay either in terms of monetary cost or loss of torque. There's better things to throw your money at on the Zed IMHO.

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test pipes (ie full decats) will not drop torque at all - in fact, torque in the midrange goes up a bit. Inexpensive to purchase, relatively simple to fit (the top bolts are a bit tight to get to, but if you're handy, they are easy to fit)

 

Stock cats are very restrictive actually - even fitting high flow ceramic cats, such as the Ultimate Racing ones we offer, produce noticeable gains. Metal substrate versions are even better, and are about 95% the flow of a full test pipe. Ultimate Racing offer these as well.

 

I ran the ceramic Ultimate Racing cats on my own car from fall 2003, when I purchased the car, to April 2007, when I installed my new engine. About 40k miles total...never any issues. I sold them to another customer, and they are on his car to this day (his car is now supercharged).

 

The ceramics maintain a stock type sound as they are denser (I don't know the cell count). They are a touch louder at the mid and top end, but it's nothing intrusive...it could easily be mistaken for a factory type sound. The metal ones have a more authoritative sound to them, as the metal cores do resonate the sound a bit more.

 

In test pipes vs cats comparison, there are a few things to consider

 

1. test pipes can sometimes cause a check engine light. It's a soft code, so it will not affect performance at all, but it does illuminate the light on the dash. The code tends to come up on cars produced after 2005. My car is a 2004, and I have test pipes, no check engine light at all

 

2. test pipes smell! If you don't mind the smell of raw exhaust, test pipes work great. If you don't want any of these odors, then a set of performance cats are the way to go

 

As far as resonated vs non, I find it has more to do with the rest of the setup vs the resonator itself. The resonator that such pipes use is very small, both in length as well as diameter, so they don't really cut down too much on noise. I've run both on my own car, and did not notice any meaningful difference between them

 

For test pipes, though they are simple items, stay away from the cheap stuff IMHO - fitment on ones like megan, etc are horrendous, and they have been known to crack at the mounting flanges. The ones we've used without issue for the older models (2002-2006) are Turbo XS and Invidia. For the 2007+ versions, TurboXS has a new set out that we've had good feedback on

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  • 2 months later...

Just thought i'd chime in on this. I fitted my JapSpeed non resonated de-cat pipes today, paired with the Nismo cat-back exhaust. It's not totally what i was expecting TBH, i didnt think it would sound like it does. I'm not sure if it's the actual pipe themselves, but there is a metallic sort of rasp noise around 4-5krpm, which im not really liking very much. On the upside, i got no CEL light, and the car does feel slighty more responsive, i'm just not sure if im happy with that noise. I will see how i get on with it this week, otherwise i will get the cat's put back on.

 

PS. Do you think that something like the Ichiba Resonated de-cat pipes will sound the same or will it stop that metallicy rasp noise in the midrange?

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Just thought i'd chime in on this. I fitted my JapSpeed non resonated de-cat pipes today, paired with the Nismo cat-back exhaust. It's not totally what i was expecting TBH, i didnt think it would sound like it does. I'm not sure if it's the actual pipe themselves, but there is a metallic sort of rasp noise around 4-5krpm, which im not really liking very much. On the upside, i got no CEL light, and the car does feel slighty more responsive, i'm just not sure if im happy with that noise. I will see how i get on with it this week, otherwise i will get the cat's put back on.

 

PS. Do you think that something like the Ichiba Resonated de-cat pipes will sound the same or will it stop that metallicy rasp noise in the midrange?

 

It won't really matter all test pipes make that noise, resonated or not, especially with the NISMO exhaust. The upside are the lower weight and more peak power/torque and low cost. Downside is the noise/smell

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I will probably end up doing that TBH, shame as the little bit of extra HP is nice, but not worth having that noise. Also i am now reading about many stories of test pipes and hfc's cracking at the joins, even with braces. So meh, i guess it was a bad idea, and i probably shouldnt have rushed into it, nevermind.

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if you're after a nice sound, not raspy, with the NISMO, I'd highly suggest the Ultimate Racing ceramic cats we offer. They outflow the stock cats, but they don't give the nasty rasp that test pipes or metal cats can. They give the NISMO a nice, deep tone

 

UltimateRacing350z-HFCat.jpg

 

The combo of these + NISMO has never disappointed me

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Just thought I'd say be carefull on your MOT aswell as I installed custom 200cell sports cats on a previous car thinking it would be road legal and the car failed the mot on emmisions :angry: and I was told they'd free up power and go throught the mot

 

My car passed with no cats ;):ninja:

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