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Discussion Starter #1
Hello all i was just wondering. I know to stay away from universal cats. However after researching this forum and the g37 forums it seems everyone needs to mention High flow cats as a replacement.

I don't mind going with resonated high flow cats. I wouldn't mind a bit of sound. However the hiss sound on deceleration would definitely annoy the **** out of me.

I was wondering if there is anything similar to the oem cats. Both of these are direct fit..... i was wondering if they would be sufficient. (i don't live in cali btw). Just looking for experiences from others.

https://mufflerexpress.com/products/2014-2015-infiniti-q50-bank-1-and-2-catalytic-converter-3-7l-v6?utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&gclid=EAIaIQobChMI-bD11OvY4wIViJ-fCh1QUwoCEAQYASABEgKLFPD_BwE

https://www.rockauto.com/en/moreinfo.php?pk=7488796&cc=3300363&jsn=8
 

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Hello all i was just wondering. I know to stay away from universal cats. However after researching this forum and the g37 forums it seems everyone needs to mention High flow cats as a replacement.

I don't mind going with resonated high flow cats. I wouldn't mind a bit of sound. However the hiss sound on deceleration would definitely annoy the **** out of me.

I was wondering if there is anything similar to the oem cats. Both of these are direct fit..... i was wondering if they would be sufficient. (i don't live in cali btw). Just looking for experiences from others.

https://mufflerexpress.com/products/2014-2015-infiniti-q50-bank-1-and-2-catalytic-converter-3-7l-v6?utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&gclid=EAIaIQobChMI-bD11OvY4wIViJ-fCh1QUwoCEAQYASABEgKLFPD_BwE

https://www.rockauto.com/en/moreinfo.php?pk=7488796&cc=3300363&jsn=8
Pretty sure both examples you used are the stock or at least OEM equivalent, for $350-$400 your not getting any improvements. I'd say go with just a highflow cats from Z1, Fast intentions or
Berk.

https://www.fastintentions.com/product_info.php/products_id/295

That little hiss your hearing is either because of a cold start or the cats simply need to settle. It's not strange after a month or two of driving for your exhaust note to change, and that's assuming you can actually
hear that hiss when your in the car with windows up.

I don't think there is anything to worry about.
 

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Hello all i was just wondering. I know to stay away from universal cats. However after researching this forum and the g37 forums it seems everyone needs to mention High flow cats as a replacement.

I don't mind going with resonated high flow cats. I wouldn't mind a bit of sound. However the hiss sound on deceleration would definitely annoy the **** out of me.

I was wondering if there is anything similar to the oem cats. Both of these are direct fit..... i was wondering if they would be sufficient. (i don't live in cali btw). Just looking for experiences from others.

https://mufflerexpress.com/products/2014-2015-infiniti-q50-bank-1-and-2-catalytic-converter-3-7l-v6?utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&gclid=EAIaIQobChMI-bD11OvY4wIViJ-fCh1QUwoCEAQYASABEgKLFPD_BwE

https://www.rockauto.com/en/moreinfo.php?pk=7488796&cc=3300363&jsn=8
I have resonated hks lower downpipes and tanabe catback sound is perfect on stock exhaust I would bet they would be barely detectable...
 

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Hello all i was just wondering. I know to stay away from universal cats. However after researching this forum and the g37 forums it seems everyone needs to mention High flow cats as a replacement.

I don't mind going with resonated high flow cats. I wouldn't mind a bit of sound. However the hiss sound on deceleration would definitely annoy the **** out of me.

I was wondering if there is anything similar to the oem cats. Both of these are direct fit..... i was wondering if they would be sufficient. (i don't live in cali btw). Just looking for experiences from others.

https://mufflerexpress.com/products/2014-2015-infiniti-q50-bank-1-and-2-catalytic-converter-3-7l-v6?utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&gclid=EAIaIQobChMI-bD11OvY4wIViJ-fCh1QUwoCEAQYASABEgKLFPD_BwE

https://www.rockauto.com/en/moreinfo.php?pk=7488796&cc=3300363&jsn=8
On my 3.7 G37, anything that free'd up the exhaust flow would pronounce the hissing on acceleration. The hiss on decel was only slight during low 2k RPM.

If you do not care about performance, grab the OEM replacement cat. If you do care about performance and have the $, grab the Fast Intentions Resonated HFC.
 

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Discussion Starter #5
Thank you all for replies. I’m more concerned with quality for the ones I posted. I know some universal cats give out after a year.

Just wanted to check that they aren’t cheap quality as I’m unfamiliar.

I would also consider some high flow cats but right now leaning toward something similar to oem.
 

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No clue which car and year you have. 🤔
 

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Discussion Starter #7
Car is 2014. Obviously the 3.7.

I have a rattle under the car.a accompanies by loss of power.... mpg and noticing a rotten egg smell from tailpipes somewhat.

The loss of power isn’t noticeable to someone who doesn’t drive it everyday. But it’s annoying to me.

I took the car to Infiniti and they claim “it’s fine”. I don’t trust them.

Indy mechanic said it could Be the cats. He isn’t 100% sure. I’m convinced it is.
 

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Car is 2014. Obviously the 3.7.

I have a rattle under the car.a accompanies by loss of power.... mpg and noticing a rotten egg smell from tailpipes somewhat.

The loss of power isn’t noticeable to someone who doesn’t drive it everyday. But it’s annoying to me.

I took the car to Infiniti and they claim “it’s fine”. I don’t trust them.

Indy mechanic said it could Be the cats. He isn’t 100% sure. I’m convinced it is.
Other CHEAP option is to pull the cat, gut it, and re-install.
 

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If the cat is bad it should pop a CEL. Any codes? You do have a code reader? Not being turbocharged going to high flo downpipes won't make a big difference.

Don't be wasted $ on parts you may not need. The cats should be covered if your mileage is low enough being EPA emission control parts. IIRC
 

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Discussion Starter #10
No check engine. No code. I checked with multiple code readers.

I’m told by a couple places it could just be the heat shield. It’s a slight rattle... but what weird is it seems to be on and off. Sometimes louder when warmed up.

Def from under the car though. Is what it is though. I’ll figure something out. Rest of the car is in great condition. Thank you for all the replies.
 

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Heat shield... my best guess.
 

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Car is 2014. Obviously the 3.7.

I have a rattle under the car.a accompanies by loss of power.... mpg and noticing a rotten egg smell from tailpipes somewhat.

The loss of power isn’t noticeable to someone who doesn’t drive it everyday. But it’s annoying to me.

I took the car to Infiniti and they claim “it’s fine”. I don’t trust them.

Indy mechanic said it could Be the cats. He isn’t 100% sure. I’m convinced it is.
Yeah that is likely a CATS issues, either a leak or failiure. Press Infiniti to repair the issue, it should be covered under warranty
as emissions are 10 years in US if I'm not mistaken.
 

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Yeah that is likely a CATS issues, either a leak or failiure. Press Infiniti to repair the issue, it should be covered under warranty
as emissions are 10 years in US if I'm not mistaken.
Emissions Defect Warranty is 8 years or 80,000 miles, whichever comes first on the cats and engine control module. The rest of the emissions control system is warrantied for 4 years or 60,000 miles.
 

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Discussion Starter #14
I would love to press Infiniti. I went to a dealer and they told me all is fine. Again I don’t believe them. As long as there is no light they can just play dumb.

Plus each dealer I go to it’s 125 to even look at it.

I have 67k so it’s well within that range for the warranty.

I don’t even mind repairing it. If it’s reasonable 500-1000 range. That’s why I was looking at different options.
 

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I just bought pre owned berk cats for my '14. Got a little louder and notice the little hiss but my throttle response seems better. I also already have an acke back stillen setup. If your replacing the cats, go high flow berk, or z1. Also Google kinetix racing high flow cats
 

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Discussion Starter #16
On high flow cats? I def don’t want anything too loud or raspy. Wouldn’t mind some slight extra noise though. FI HFC seem to fit this category.

The 2.25 piping is a little extra than the 2.5. My understanding is the 2.25 is more uniform with the stock exhaust.... and that could minimize any potential hiss?

Sorry for the newb questions. I’m ok with cars but never really considered high flow cats.
 

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Discussion Starter #17
Hello all sorry to revive an old thread. Apparently the noise i'm hearing if from the flex pipe starting to fail. There is a small leak in one or both of them. Place i brought the car to showed me this. When they rev the engine you can distinctly see the flex pipe vibrating on one side, and hear the sound underneath.

I had a place tell me they can wield a new one on for 150-200 dollars.

Another place told me it may be worth it to replace the whole y pipe. But thats gonna run me like 500-600 dollars.

Is one better than the other in this situation?
 

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I have my stock exhaust. No clue where you live.
 

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Discussion Starter #20
Hey thanks for replies. IS the Megan y pipe going to be noisier? The rest of my exhaust system is stock.
 
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