AMS Full Downpipes Catted Pkg

[HarryBo]

Hi all,

Looking at the following to add power to my '24 Z Nismo. Keeping stock exhaust adding full downpipes, cold air intakes, intercoolers, and custom EcuTek tune. Thoughts and HP Torque gains estimates? 100HP? Looks like about $12k Cdn installed.

ALP.28.05.0002-2
AMS Performance VR30DDTT Street Full Downpipes

MMINT-Z-23
Mishimoto 2023+ Nissan Z Air-to-Water Intercooler Kit

AMS Performance 2023+ Nissan Z Cold Air Intakes

AMS.47.13.0101-1
AMS Performance Nissan Z Custom ECU Calibration Service

 

[KrackaC8]

Keeping the stock catback exhaust makes the rest of this futile, unfortunately. That is your #1 biggest restriction.

You will want to pair the Mishimoto heat exchanger to go along with their intercoolers.

 

[HarryBo]

Keeping the stock catback exhaust makes the rest of this futile, unfortunately. That is your #1 biggest restriction.

You will want to pair the Mishimoto heat exchanger to go along with their intercoolers.

Thanks for input. I thought that downpipes were biggest restriction and that Nismo catback exhaust wasn't too bad.

Indeed, heat Exchanger on the next potential list, though again Nismo oem thought was ok.

Thanks.

 

[KrackaC8]

Thanks for input. I thought that downpipes were biggest restriction and that Nismo catback exhaust wasn't too bad.

Indeed, heat Exchanger on the next potential list, though again Nismo oem thought was ok.

Thanks.

The factory Nismo catback is the same as the rest of the trims; Nismo does sell an aftermarket upgrade though which is much better!

Doing the heat exchanger at the same time as the intercoolers will save you from having to vacuum bleed the cooling system twice.

 

[kevinbonds]

Hi all,

Looking at the following to add power to my '24 Z Nismo. Keeping stock exhaust adding full downpipes, cold air intakes, intercoolers, and custom EcuTek tune. Thoughts and HP Torque gains estimates? 100HP? Looks like about $12k Cdn installed.

ALP.28.05.0002-2
AMS Performance VR30DDTT Street Full Downpipes

MMINT-Z-23
Mishimoto 2023+ Nissan Z Air-to-Water Intercooler Kit

AMS Performance 2023+ Nissan Z Cold Air Intakes

AMS.47.13.0101-1
AMS Performance Nissan Z Custom ECU Calibration Service

It would be better to understand your goals. The Stock Nismo sounds and performs great, and come from the factory with improved cooling, so not sure if intercoolers would be high on my list. Are you going to track the car, or just enjoy it as a weekend cruiser?

 

[HarryBo]

It would be better to understand your goals. The Stock Nismo sounds and performs great, and come from the factory with improved cooling, so not sure if intercoolers would be high on my list. Are you going to track the car, or just enjoy it as a weekend cruiser?

No tracking. Just wanting to squeeze a bit more power, and be that much more exclusive.

Maybe just airbox, downpipes, tune?

 

[HarryBo]

The factory Nismo catback is the same as the rest of the trims; Nismo does sell an aftermarket upgrade though which is much better!

Doing the heat exchanger at the same time as the intercoolers will save you from having to vacuum bleed the cooling system twice.

I see. Don't want restriction in exhaust. So thinking downpipes, and catback, airbox, tune. No intercooler or heat exchanger as not tracking.

 

[KrackaC8]

I see. Don't want restriction in exhaust. So thinking downpipes, and catback, airbox, tune. No intercooler or heat exchanger as not tracking.

Being a Nismo, especially for only street use, you're probably just fine on the stock heat exchangers. Always something you could upgrade down the road when/if you get the itch for more.

 

[kevinbonds]

No tracking. Just wanting to squeeze a bit more power, and be that much more exclusive.

Maybe just airbox, downpipes, tune?

If it were me and I had a nismo, the only thing I would do, for bang for buck. Resonated Lower Downpipe and a high quality 2.5 to 3 inch exhaust and a tune. That's it, call it a day.

 

[FSUZ33]

If it were me and I had a nismo, the only thing I would do, for bang for buck. Resonated Lower Downpipe and a high quality 2.5 to 3 inch exhaust and a tune. That's it, call it a day.

LOL, my list was smaller than that when I got my NISMO. One of the reasons I wanted that model. And look at me now? It's a sickness only kept contained by a tag-team combination of my bank account and my wife.

 

[HarryBo]

LOL, my list was smaller than that when I got my NISMO. One of the reasons I wanted that model. And look at me now? It's a sickness only kept contained by a tag-team combination of my bank account and my wife.

Haha! It's indeed a slippery slope.

 

[MAPerformance_]

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[HarryBo]

Hi all,
Here is an ChatGPT summary of my final decision on upgrades:

Redoing it properly:

For a 2024 Nissan Z NISMO, Nissan rates the car at 420 hp and 384 lb-ft at the crank from the factory. In wheel terms, a stock NISMO typically lands well below that on a dyno because of drivetrain loss, but the official baseline is 420/384. (Nissan USA)

With the parts on your invoice — AMS cold air intakes, AMS street full downpipes, AMS custom ECU calibration, and AMS intercoolers — the realistic final output on pump gas is about:

• 480–510 WHP
• 450–500 WTQ

The most likely strong, streetable result is about:

• 490–500 WHP
• 470–490 WTQ

That final range is an inference based on Nissan’s stock baseline plus AMS’s published intake gains, AMS’s published “about 70 WHP over stock” custom-calibration example, AMS’s claim that full downpipes add another 20 hp over lower downpipes on a tuned VR30, and the intercooler’s role in preserving power under heat rather than creating a huge standalone peak-gain number. (Nissan USA)

Gain from each part
1) AMS cold air intake
AMS says its Nissan Z cold air intake has a 23% average cross-section increase over OEM intake pipes and can deliver 10+ WHP out of the box or 15+ WHP with ECU tuning. For your build, the realistic gain contribution is:

• +10 to +15 WHP
• +5 to +10 WTQ

This is a real gain, but it is still a supporting mod, not the main event. (AMS Performance)

2) AMS custom ECU calibration
AMS publicly described a custom Nissan Z calibration as producing approximately +70 WHP over stock on its SEMA build. That is the biggest single gain source in your package. For a streetable pump-gas NISMO, I’d treat the tune as worth roughly:

• +60 to +80 WHP
• +50 to +70 WTQ

That range is partly based on AMS’s own “approximate 70 WHP increase over stock” statement and partly on inference, because exact results vary with octane, dyno, weather, and how aggressive the calibration is. (AMS Performance)

3) AMS street full downpipes
AMS says its street lower downpipes use full 3-inch mandrel-bent stainless tubing to improve flow, boost response, and spool. More importantly, AMS says its full downpipes produced 20 horsepower more than its lower downpipes on a tuned VR30 test car, with earlier power and better turbo spool. For your build, a realistic contribution from the move to full catted street downpipes is roughly:

• +35 to +55 WHP versus stock exhaust path
• +35 to +50 WTQ

And specifically, compared with running only lower downpipes, the full downpipe setup is worth about:

• +15 to +20 WHP
• +10 to +20 WTQ

That extra gain is where the full downpipes justify their cost. (AMS Performance)

4) AMS intercoolers
AMS says its Nissan Z intercoolers have a 70.4% larger core than factory, with larger inlets, outlets, and coolant ports. AMS positions them as a heat-management upgrade, not just a peak-number part. So the real standalone “gain” is modest on the first pull, but large in terms of holding power repeatedly. Realistically:

• +0 to +10 WHP on the first cool pull
• +10 to +25 WHP preserved under repeated hard pulls / heat-soak conditions
• similar story for torque: modest peak gain, more meaningful preservation in back-to-back runs

That is why intercoolers matter so much on the VR30 even though they don’t make for flashy standalone dyno claims. (AMS Performance)

Minimal gain from adding a cat-back exhaust
For the Nissan Z, NISMO says its cat-back exhaust gives measurable reduction in back pressure, and one listing cites a 45% reduction in back pressure for the race/track version. That absolutely helps flow and sound, but on your already-tuned, downpipe-equipped setup, the incremental horsepower gain is usually small because the bigger restriction is upstream at the turbo/downpipe area. Realistically, adding a cat-back after your current package is usually only worth about:

• +5 to +10 WHP
• +5 to +10 WTQ

The main reasons to add the cat-back are sound, tone, aesthetics, and a little extra top-end flow, not a major power jump. That gain range is an inference from the fact that Nissan/NISMO emphasize back-pressure reduction, while the bigger published power jumps in this platform come from tune and downpipes. (z1motorsports.com)

Minimal gain from adding a heat exchanger
AMS says its Nissan Z heat exchanger has 42% more frontal surface area, a core that is twice as thick as OEM, and 200% more coolant capacity than stock. That means it increases the thermal capacity of the intercooler circuit. Like the intercooler, this is mostly a consistency part, not a “big peak dyno number” part. Realistically, adding the heat exchanger to your existing setup is usually worth only about

• +0 to +5 WHP on a cool first pull
• +5 to +15 WHP preserved during repeated pulls, hot weather, or longer runs

So again, it is more about keeping the car from laying down power as temperatures rise. (AMS Performance)

Why the AMS intercooler is superior
The AMS intercooler is superior because it is not just “slightly bigger.” AMS says the core is 70.4% larger than stock, with upsized air inlets, outlets, and coolant ports, plus CNC billet end tanks. In plain English, that means:

• more heat can be absorbed and shed
• airflow path is less restrictive
• coolant flow capacity is improved
• the system is better prepared for repeated boost events

That matters most on a tuned VR30, because heat is what starts stealing timing, consistency, and repeatability. So the AMS intercooler’s superiority is not that it magically adds huge peak horsepower on one hero pull. It is that it lets the tune and downpipes keep delivering closer to their full value over and over again, especially when ambient temps are up or you do repeated pulls. That is why I rate it as a better strategic upgrade than a cat-back or heat exchanger if you are choosing priorities. (AMS Performance)

Best way to think about the whole package
A sensible breakdown for your 2024 Z NISMO looks like this:

• Stock: 420 hp / 384 lb-ft crank; roughly stock wheel output below that baseline (Nissan USA)
• Tune only: biggest jump, roughly +60 to +80 WHP (AMS Performance)
• Intake added: another +10 to +15 WHP (AMS Performance)
• Street full downpipes added: another +35 to +55 WHP, with the full setup worth about 20 hp over lowers on AMS’s VR30 testing (AMS Performance)
• Intercooler added: little headline peak gain, but major consistency and heat-soak resistance (AMS Performance)
• Cat-back added later: usually only +5 to +10 WHP (z1motorsports.com)
• Heat exchanger added later: usually only +0 to +5 WHP peak, but better sustained output in heat (AMS Performance)

Bottom line
For your exact invoice parts, the honest expectation is:

~490–500 WHP and ~470–490 WTQ on pump gas if the tune is strong but sensible. (Nissan USA)

And the honest verdict on the “extras” is:

• Cat-back exhaust: mostly sound and modest flow improvement
• Heat exchanger: mostly repeatability insurance
• AMS intercooler: the most meaningful supporting hardware because it protects the whole build from heat fade

 

[KrackaC8]

@HarryBo in the above AI seems to be talking about the aftermarket Nismo catback, not the factory catback that comes equipped on the Nismo trim, which is the same as all other Z trims.

 

[HarryBo]

@HarryBo in the above AI seems to be talking about the aftermarket Nismo catback, not the factory catback that comes equipped on the Nismo trim, which is the same as all other Z trims.

It maybe. However I reran Chat with OEM Performance/Nismo exhaust and talked with my local tuner - the 5-10hp gain estimate holds. Where the big difference would be in applications with upgraded turbos with substantial airflow increases and output targets well above 500 hp.

WHEN CAT-BACK MATTERS MORE

It becomes more relevant if:

• You go bigger turbos
• You push 550+ WHP
• You run ethanol / higher boost

At your level (~500 WHP):

• Gains are minimal