Downpipes & Best Practices

SavedByFaith_

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Hello all!

I have some questions for those gearheads / tuners.
The Z is my first Car that I'll be modifying to this degree, I've always been interested in Tuner / Modded cars with some friends having done mods to their cars and always in general interest of reading / watching up on this stuff. But when it comes down to the finer details and the mechanics of it all, I'm lackluster. So i'm here with a few questions.

Intent & Objective:
My number one intent with modding (at this time) is for Sound. I want the Z to sound as it looks, as it should. I find the car is very lackluster in sound... Whether it's Standard or Sport mode, you really don't hear anything until around 4-4.5k RPM, and even at that it's mediocre carrying into the 6-6.5k RPM.
I'm not looking to "be that guy" ripping a fart machine down the road - but am looking for a deeper and more thorough growl / roar in the low and higher RPMs.

My Proposed Solution:
After watching the reviews, and multiple other videos, my understanding is that the full downpipe is a bottle neck on the whole exhaust flow and in turn the Sound. The small pipe (1.25in or something like that) paired with the two catalytic converters on the upper & lower pipe seem to really restrict the exhaust flow. Of course, the piping in the exhaust mid and axle aren't any better with a similar 1.25in pipe.

So I figured, let's swap it out - this is when I bought myself the full single Catted (GESI OBD2 Sport [Gen-1, 300 Cell Count]) MAP downpipe paired with the MAP full Cat-Back Exhaust.

The Dilemma:
I got my mechanic / garage booking for early next week and as I've gotten closer to the date, I'm crossing my t's and dotting my i's and getting a little nervous.

a) Check-Engine Light.... I understand that this is very possible of happening as the second cat off the lower downpipe will be removed. I believe this is used to check "cold-start emission? and/or readiness / inspection testing?" and failing this test will throw a CEL.
I'm thinking and reading that an O2 Spacer (Spark Plug Defouler) may help in avoiding this CEL - anyone have thoughts with this?

b) Negative Repercussions on the Drivetrain..... I'm reading that with a stock tune and upgraded turbo back pipe diameter will cause "wastegate / back pressure".
I'm not entirely sure what all this is about, but can sort of understand what is happening and how the ECU (although smart) may not be able to auto-correct / adjust the "metrics" to account for the increased flow of the entire turbo back.
Is this true? will there be negative repercussions if running a full turbo back with a stock tune?
I totally understand how a tune (I'd be looking into ECUTek from Panda, Z1 or AAM) would "adjust" this and correct the metrics for the fuel and all that fancy stuff to obviously make the best of the turbo back but also ensure all the mechanics are running smooth and avoid any "harm".

c) Warranty Shenanigans.... I totally understand that if I mess with the downpipes and give it a ECUTek Tune, I'm certainly blowing away any and all my warranty - pretty much blacklisting myself.... (even if it's jsut full pipes and no tune)
In general, would love to hear from folks about this and their experience / stories.
In contrast, my bare minimum plan is to solely install the MAP CBE and leave the stock downpipe - would love to hear form anyone who just had a CBE and warranty / dealer service stories (I'm guessing I'd still be flagged, but maybe some more wiggle room to hold "part" of the warranty?)

Final Thoughts:
I stated how I want Sound above all else at this point with the Z - this is certainly true, although I do have aspirations to further mod it with the items mentioned above and more.
Just after spending nearly two weeks with the Car, it changed my perspective a little right... Care for her, want to have her forever and minimize my maintenance and risk with her for the time-being, while still being able to fully enjoy her with each drive. Perspectives change... before having the car, I was totally down for all this and risk the warranties and manufacturer's role in the early life of the car. But now, having her in my hands, I want her to be in the best condition; the thought of her having some problems due to the manufacture and myself throwing out the warranty has me in this dilemma.

All in all, I know there isn't a clear-cut decision and it's based on my personal risk tolerance - just looking to hear some opinions and more importantly the mechanical facts of the mods and their possible combo outcomes.

Thanks!
 

Blackbeard

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I know the down pipes with out cats is always going to throw a code and done high flow cats unless the maker says it isn’t going to but sometimes they will but u have a guarantee but most of the time u will need a tune. The defouler is hit or miss and sometimes it will just wear out and throw a code later
 
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SavedByFaith_

SavedByFaith_

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I know the down pipes with out cats is always going to throw a code and done high flow cats unless the maker says it isn’t going to but sometimes they will but u have a guarantee but most of the time u will need a tune. The defouler is hit or miss and sometimes it will just wear out and throw a code later

Yup understand that catless DPs will throw the code, hence why i got high-flow catted.
Still, from my research, none of the vendors are claiming "no CEL code" -figured the o2 spacer would decreases the chances of the CEL.

I'm much more concerned with running full turbo-back without a tune...would this harm the drivetrain in any way?
 

Blackbeard

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you have high flow cats so it shouldnt be a issue, your just not getting the full potential if it were tuned bu if u dont feel comfortable you could just run cat back for the time being
 
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SavedByFaith_

SavedByFaith_

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you have high flow cats so it shouldnt be a issue, your just not getting the full potential if it were tuned bu if u dont feel comfortable you could just run cat back for the time being
For sure, I def want to run the full downpipe / turbo back for the aggressive sound.
Just the thought of repercussions (back-pressure?) without a proper tune is having me doubt and just just the CBE in for now until I'm ready to commit to a ECU Tune.
 

Go2ZZZ

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Welcome to the forums!

I personally went with Fast Intentions exhaust and matched it with their LOWER downpipe.
I also dont want to "be that guy" with that loud exhaust. Fast Intentions nailed it for people like us who just want deep tones. For performance, a full down pipe is recommended. If its sound you looking for, a lower downpipe would help and give performance as well ( not as much as the FDP).

LDP should not give you a CEL but will with a FDP (but a tune will fix that). Any Downpipe you put, will most likely void your warranty. It can depend on the service department really, some are ok most are not.

Labor is also a lot more for the FDP. Another option is a JB4 Piggyback tune. If any warranty work needed, you can easily detach JB4 and remove the LOWER DP much easier and make it stock much faster. Just my 2 cents.

CHEERS!
 
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SavedByFaith_

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Welcome to the forums!

I personally went with Fast Intentions exhaust and matched it with their LOWER downpipe.
I also dont want to "be that guy" with that loud exhaust. Fast Intentions nailed it for people like us who just want deep tones. For performance, a full down pipe is recommended. If its sound you looking for, a lower downpipe would help and give performance as well ( not as much as the FDP).

LDP should not give you a CEL but will with a FDP (but a tune will fix that). Any Downpipe you put, will most likely void your warranty. It can depend on the service department really, some are ok most are not.

Labor is also a lot more for the FDP. Another option is a JB4 Piggyback tune. If any warranty work needed, you can easily detach JB4 and remove the LOWER DP much easier and make it stock much faster. Just my 2 cents.

CHEERS!

Thanks for the welcome!

Yea... kicking myself for not going LDP only given I only wanted to buff up the sound!
At this point, worried with CEL, but moreso with hurting the turbo through wastegate / backpressure even with a Catted Full Downpipe.
 

TheRoyalStig

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Welcome to the forums!

I personally went with Fast Intentions exhaust and matched it with their LOWER downpipe.
I also dont want to "be that guy" with that loud exhaust. Fast Intentions nailed it for people like us who just want deep tones. For performance, a full down pipe is recommended. If its sound you looking for, a lower downpipe would help and give performance as well ( not as much as the FDP).

LDP should not give you a CEL but will with a FDP (but a tune will fix that). Any Downpipe you put, will most likely void your warranty. It can depend on the service department really, some are ok most are not.

Labor is also a lot more for the FDP. Another option is a JB4 Piggyback tune. If any warranty work needed, you can easily detach JB4 and remove the LOWER DP much easier and make it stock much faster. Just my 2 cents.

CHEERS!
Oh wait, so the LDP still maintains a stock cat?

I didn't realize stock had 4 cats so I really thought the LDP made the car catless and thus wasn't looking at them.

If they keep a cat then this is route ill likely be going too. Thanks!

And OP, personally I wouldn't be going too hard without a tune since the downpipe will be affecting the turbo spool. I would be keeping it out of boost until I had the tune.

But thats just based on how other cars react not directly the Z.
 
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SavedByFaith_

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Oh wait, so the LDP still maintains a stock cat?

I didn't realize stock had 4 cats so I really thought the LDP madevthr car catless and thus wasn't looking at them.

If they keep a cat then this is route ill likely be going too. Thanks!

And OP, personally I would be going too hard without a tune since the downpipe will be affecting the turbo spool. I would be keeping it out of boost until I had the tune.

But thats just based on how other cars react not directly the Z.
Yup, the OEM is two piece, upper & lower downpipe with a Cat on each.

Thanks for the recommendation.
Will go with the Cat-back Exhaust for now and leave the downpipe as stock.
No point spending money on a LDP, when I already have FDP.

Need to know invest in a ECU Tune, probably through EcuTek.
 

Maximus

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So I was also in the same boat as far as not wanting to throw a CEL with downpipes. I opted for the AMS race full downpipes (because they were cheaper and I want optimal gains) mated to a Z1 Single outlet exhaust because I felt the sound of that exhaust is not loud and raspy but just right. I contacted AMS and was told the car shouldn’t throw a CEL as long as they’re installed properly (probably because of the extended bunts for the O2 sensors). I do plan on getting the car tuned on a dyno with EcuTek after install of the downpipes and exhaust
 
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SavedByFaith_

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So I was also in the same boat as far as not wanting to throw a CEL with downpipes. I opted for the AMS race full downpipes (because they were cheaper and I want optimal gains) mated to a Z1 Single outlet exhaust because I felt the sound of that exhaust is not loud and raspy but just right. I contacted AMS and was told the car shouldn’t throw a CEL as long as they’re installed properly (probably because of the extended bunts for the O2 sensors). I do plan on getting the car tuned on a dyno with EcuTek after install of the downpipes and exhaust
Thanks for the info champ!
Your process is what I should be doing but...

I figured I can run a catted downpipes (hoping no CEL, but bought o2 spacers anyway) without a tune and enjoy that for a while.

After extensively reading about the wastegate function, back pressure, boost creep / spikes, don't want to run the risk of any turbo damage / accelerated wear without a tune now

So I'll just install the CBE next week and keep it as is for this year.

Already contacted a reputable and licensed EcuTek dealer in my local area and discussing the details for tune and dyno time.
Will visit the shop this year, build a rapport and plan to do the catted downpipes and tune next year with the shop.

Super tempted to do it all now...
But rather enjoy the stock experience and run low risk if any recalls / lemon type stuff happens.
 

Maximus

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Thanks for the info champ!
Your process is what I should be doing but...

I figured I can run a catted downpipes (hoping no CEL, but bought o2 spacers anyway) without a tune and enjoy that for a while.

After extensively reading about the wastegate function, back pressure, boost creep / spikes, don't want to run the risk of any turbo damage / accelerated wear without a tune now

So I'll just install the CBE next week and keep it as is for this year.

Already contacted a reputable and licensed EcuTek dealer in my local area and discussing the details for tune and dyno time.
Will visit the shop this year, build a rapport and plan to do the catted downpipes and tune next year with the shop.

Super tempted to do it all now...
But rather enjoy the stock experience and run low risk if any recalls / lemon type stuff happens.
Bro I hear ya on everything!

There are times when I’m driving and am just like “car is fine, runs great, cruising is noiseless…” etc.

But there’s the other side of me that says “I want thing to be mean, sound like a race car, eat raw meat and shit vegetables….” Lol.

I have a guy around here that predominantly deals with Nissan / Infinity at his shop, is a certified Nissan tech, had an old 240 that he used to race and uses EcuTek to tune all his cars. I also know a manager at the local dealership here so on those fronts, I feel fortunate. But at the same time, I want my car to sound better, run better but at the same time, be reliable without having to work on the car.

It’s a double edged sword we all have to risk and deal with but….it is what it is unfortunately.
 
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SavedByFaith_

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Bro I hear ya on everything!

There are times when I’m driving and am just like “car is fine, runs great, cruising is noiseless…” etc.

But there’s the other side of me that says “I want thing to be mean, sound like a race car, eat raw meat and shit vegetables….” Lol.

I have a guy around here that predominantly deals with Nissan / Infinity at his shop, is a certified Nissan tech, had an old 240 that he used to race and uses EcuTek to tune all his cars. I also know a manager at the local dealership here so on those fronts, I feel fortunate. But at the same time, I want my car to sound better, run better but at the same time, be reliable without having to work on the car.

It’s a double edged sword we all have to risk and deal with but….it is what it is unfortunately.
Couldn't have said it better myself!

I'm just stoked overall with everything.
Great new chapter being unfolded in front of us, can't wait to experience it all!

I'll def post some content when I get the MAP CBE done next week.
 

Maximus

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Couldn't have said it better myself!

I'm just stoked overall with everything.
Great new chapter being unfolded in front of us, can't wait to experience it all!

I'll def post some content when I get the MAP CBE done next week.
Looking forward to it 👍🏼🤘🏽
 

Jah_Happy

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Any updates here? Just curious how everything turned out. Are you guys still enjoying your setups? Im looking into exhaust/ downpipe setups now and have the same questions regarding CEL's and noise / drone, etc.
 
 





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