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For those thinking about a "performance" exhaust system

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#61
No they don't. Maybe in the Imaginationland dealership, but not in the real world.

Oh ya, that's totally a stock GT-R. Show me on the Nissan website where I can buy that car. :rolleyes:
BMW M/competition models get a full tune for the engine to be fully unlocked. You need to have a “break-in period” and you will have launch control active after the update. It’s probably a butt dyno effect after that.

go to any JDM auction you’ll find plenty of rwd GTR. It be right side driver seating configuration FYI. Maybe a gremlin will arrive with your purchase.
 

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#63
BMW M/competition models get a full tune for the engine to be fully unlocked. You need to have a “break-in period” and you will have launch control active after the update. It’s probably a butt dyno effect after that.

go to any JDM auction you’ll find plenty of rwd GTR. It be right side driver seating configuration FYI. Maybe a gremlin will arrive with your purchase.
Again, no there isn't a tune. It's the break in service. Anyone that says it's different after the service is just because the engine is loosening up with use and because they'll now use the full rev range.

Again, that's not a GT-R if RWD. That's a GT-S or GT-T. Different trim and motor. What does drive side have to do with anything? Yes most people know what side the steering wheel is on in Japan, England, and Australia.
 

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#64
Again, no there isn't a tune. It's the break in service. Anyone that says it's different after the service is just because the engine is loosening up with use and because they'll now use the full rev range.

Again, that's not a GT-R if RWD. That's a GT-S or GT-T. Different trim and motor. What does drive side have to do with anything? Yes most people know what side the steering wheel is on in Japan, England, and Australia.
I’ve driven some in England and extensively in Japan when I was basically living there…never did get used to right hand drive. I think I dislike the USVI even more with left hand drive cars on the wrong side of the road. lol
 

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2020 Explorer ST
#65
I’ve driven some in England and extensively in Japan when I was basically living there…never did get used to right hand drive. I think I dislike the USVI even more with left hand drive cars on the wrong side of the road. lol
The only RHD car I've driven was a buddy's R32 GT-R. I kept trying to start in 5th. Used to 1st being closest to me!
 

93coupe

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#66
I'll throw this in here for conversation purposes. I own a 1993 mustang true st/NT car that is powered by a dart 408" with a single billet FI s484 turbo. I have ran both a single 5" diameter downpipe with a 5" id/od short muffler fender exit exhaust total length 36". Then i custom fabricated a single 4" that snakes through my k member with a y pipe to dual 4" pipes/4" bullet mufflers exiting at the rear bumper through 4" tailpipes.
The 4" rear exit does ever so slightly take longer to spool the turbo but killing the cabin drone (from fender exit) was the initial reason for changing because it is street driven. There was ZERO changes from a performance/hp aspect accept the additional weight.
-Now I'm going to throw this one out there, aluminum downpies/exhaust which have ZERO heat retention.
 

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Fort Lauderdale
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2022 Explorer ST
#67
@TMac what sort of HP would the stock exhaust support?
 

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TMac

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Thread Starter #68
@TMac what sort of HP would the stock exhaust support?
We know from several people who have posted dyno numbers it supports 500+ WHP on e50. The reality is the stock exhaust will support the limits of the stock turbos. FIgure approx 600 crank HP. Above that, you need to upgrade turbos, downpipes, etc. I don't know of anyone who has updated the turbos while on the stock exhaust system, so I can't really say what the limits are. Mathematically, (and this doesn't take into account the flow restrictions of the mufflers which I do not know), a dual 2.25" system would support north of 700 hp.
 

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#69
Coming from the DSM world (Mitsu 4g63) it blows my mind that the stock exhaust on this flows so well to support so much power and yet remain so refined. My 99 eclipse was like taking a cork out of a bottle, exhaust wasn't optional to make power it was necessary.
 

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TMac

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Thread Starter #70
Never modded a DSM; had a friend with a Galant Vr-4, but I'm curious- how was boost control once you changed the exhaust? Any overboost? I had a '93 Typhoon. These were equipped with a small turbine and could reach full boost at very low rpms. So much so that there was positive boost at 70mph just cruising down the highway! They were well known to overboost significantly with exhaust upgrades. Which of course, made an exhaust upgrade seem like it added a lot of horsepower!
 

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#71
This was back when manual boost controllers were a thing. With a MBC there were boost spikes for sure, and depending on the turbo and any wastegate mods it could get a little hairy. The Profec helped, but it was always present a little.
 

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#72
Never modded a DSM; had a friend with a Galant Vr-4, but I'm curious- how was boost control once you changed the exhaust? Any overboost? I had a '93 Typhoon. These were equipped with a small turbine and could reach full boost at very low rpms. So much so that there was positive boost at 70mph just cruising down the highway! They were well known to overboost significantly with exhaust upgrades. Which of course, made an exhaust upgrade seem like it added a lot of horsepower!
The onboard gauge in my GTI shows 10-12PSI when cruising 75-80. I’m not sure I believe it. lol
 

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TMac

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Thread Starter #73
I thought I'd add another post to this thread. There are many posts like @JeffSpicoli above and between that post and today, I've seen scores of similar posts. There seems to be many people who think the first thing one "MUST" do to achieve performance is to swap the factory exhaust and intake. For the ST, I completely disagree.

But where does this idea come from? Vendors trying to sell exhausts? People just wanting more vroom? Or something else?

Let me put this forward- it's because the ST is not your Dad's (or your's) 20-30 year old turbo vehicle. The conventional wisdom about older vehicles (perpetuated by vendors, and those who bought the products) is that there are huge performance gains with an exhaust and intake.

What you might not realize is the technology was nowhere near where it is today. Any idiot could muck about with an aquarium valve to screw with boost pressure. You could also play games with mechanical adjustment of the wastegates; and buy manual or even electronic wastegate controllers. Which would work...until you lost that rod bearing or piston.

No manufacturer wants pissed off customers, nor do they wish to replace engines under warranty. So, what might be a solution in the days before the sort of technology we now have in a turbo vehicle? Simple, use the intake and exhaust as additional boost control mechanisms. A restrictive exhaust and/or intake provides a little bit of insurance to the engine when someone ignorant plays boost games.

This then led to the idea that you "had" to change the factory intake and exhaust to make gains- and this was correct thinking at the time. Of course that high-flow intake and exhaust led to thousands of destroyed engines since that very restriction was part of the manufacturers' boost control strategy. And once you overrode that capacity, unless you had a good tuner, you were also overriding the injector capacity, the timing correction capacity, the MAF sensors, etc.

The ST is not in that category. The intake and exhaust are NOT a limited factor at 25-35% over the factory HP (mass airflow) rating.

If you go above that 25-35%, you might need to think about playing with the intake or exhaust. But to achieve that, you'd have to replace the stock turbos. Even then, mathematically, the stock exhaust system should easily be good for 650+ HP (that doesn't include the downpipes which I would replace along with the turbos).

Now as posted earlier, if you are only interested in some acoustical gain- buy whatever you want, it's your money. But don't post about butt-dyno HP gains (and God forbid MPG gains) from intakes and exhausts and expect to be taken seriously.
 

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STYarnham

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#74
Thank you! I try my best, while hiding most of the math. I haven't read any posts by Mr. Duck, but I definitely don't have the patience to do 1.7 million different combinations!
Could you show the math demonstrating inhibited output from 3” system compared to stock? I think it would be helpful to see, actually.
 

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#75
Although I agree on diameter not being a restriction, there are gains to be had with Down Pipes. I’ve seen at least 5 independent Dyno runs showing gains of several different Down Pipes. The range was 20-27whp. I’m sure this is dependent on power level, as there is likely no gains at stock power levels.

I’ve also seen a 900hp motor on a engine Dyno gain a measly 30hp going from a 3” muffled exhaust to a open 4” pipe.


Sent from my iPhone using Tapatalk
 

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TMac

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Thread Starter #76
Although I
agree on diameter not being a restriction, there are gains to be had with Down Pipes. I’ve seen at least 5 independent Dyno runs showing gains of several different Down Pipes. The range was 20-27whp. I’m sure this is dependent on power level, as there is likely no gains at stock power levels.

I’ve also seen a 900hp motor on a engine Dyno gain a measly 30hp going from a 3” muffled exhaust to a open 4” pipe.


Sent from my iPhone using Tapatalk
At one time, I was going to put up a post about dynos. They are a great tool for comparison, but in the real world, for something like an exhaust, they don't reflect actual results on the track. When you're doing a dyno pull, it's in a set gear at the load value of the dyno. For tuning purposes that's perfect because it's repeatable.

As I mentioned in post #20 in this thread, maintaining velocity in the exhaust system is beneficial to throttle modulation and shifting which isn't reflected on a dyno. So yes, you made more peak HP on the dyno, but those gains won't necessarily be realized at the track. Obviously, if the gains were say 10% or more, you needed extra diameter in the exhaust.
 

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#77
At one time, I was going to put up a post about dynos. They are a great tool for comparison, but in the real world, for something like an exhaust, they don't reflect actual results on the track. When you're doing a dyno pull, it's in a set gear at the load value of the dyno. For tuning purposes that's perfect because it's repeatable.

As I mentioned in post #20 in this thread, maintaining velocity in the exhaust system is beneficial to throttle modulation and shifting which isn't reflected on a dyno. So yes, you made more peak HP on the dyno, but those gains won't necessarily be realized at the track. Obviously, if the gains were say 10% or more, you needed extra diameter in the exhaust.
Several have posted 2 10ths gains with just adding aftermarket DPs. The stock cats and DP design is a restriction well before you run out of turbo on this platform. HP gain is HP gain especially when there is a move improvement under the curve.

Heck I’m running a single 3” with 700+hp on my truck. I don’t expect that I would see significant gains ( if any) going to larger or dual piping.


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TMac

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Thread Starter #78
Several have posted 2 10ths gains with just adding aftermarket DPs. The stock cats and DP design is a restriction well before you run out of turbo on this platform. HP gain is HP gain especially when there is a move improvement under the curve.

Heck I’m running a single 3” with 700+hp on my truck. I don’t expect that I would see significant gains ( if any) going to larger or dual piping.


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I wasn't really commenting on the gains from downpipes as much as just commenting in general on using a dyno to judge gains from larger diameter exhausts.
 

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#79
Has anyone straight piped their ST yet?
 

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#80
Has anyone straight piped their ST yet?
Quite a few and it’s the most absolutely horrid sounding thing…hard pass on that idea.
 



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