Downpipes and mid pipe discussion...

[elijahallen]

Hey guys, I've had the car a week now and am ready to improve on the stock performance. I have ordered Unitronic Stage 2 software and will run the Stage one until I accumulate the parts needed for stage two. In the past my S model cars all came with great flowing exhaust and most of the time upgrading exhaust was more for sound than power. Is the exhaust on this car actually restrictive at the downpipe and mid pipe sections or is this more of a trend to sell more parts and be louder? Is there any before and after dyno charts that show a justifiable improvement? My goal with this car is to keep sound as close to stock as possible but make stage 2 power, if that is an impossible feet and I have to upgrade downpipe and mid pipe then so be it but if I can get away with just downpipe or just leaving it stock and upgrading intake and intercooler that would be ideal. Also if anyone has tuned out or has a solution to stop the start up crackle I would love to see that gone. I wish they would have made that only happen in dynamic so you at least had the option to not turn everyones head your way when you start the car. Thanks for any insight on these inquiries.

[Evilevo]

Well you can't run the stage 2 tune with a factory downpipe soooooo

[LJS5]

You can make close to stage 2 power on Stage 1 E85 tune, without needing DP.

I ended up going the Stage 2 route since i'll only run 93 oct and had to get DP.
I've been seeing a few people run stage 2 without aftermarket DP, however, looking at both units side by side, i'd guess there is definitely a restriction in the stock DP.
If wastegate rattle is a concern, you can try IE or APRs catted DP to minimize the wastegate rattle but i hear it's still pretty noticeable.
As for the loud startup, i just ordered exhaust valve controller to address that. It lets you control if you want flaps open or closed on startup.

[Evilevo]

You can make close to stage 2 power on Stage 1 E85 tune, without needing DP.

I ended up going the Stage 2 route since i'll only run 93 oct and had to get DP.
I've been seeing a few people run stage 2 without aftermarket DP, however, looking at both units side by side, i'd guess there is definitely a restriction in the stock DP.
If wastegate rattle is a concern, you can try IE or APRs catted DP to minimize the wastegate rattle but i hear it's still pretty noticeable.
As for the loud startup, i just ordered exhaust valve controller to address that. It lets you control if you want flaps open or closed on startup.

Yeah but he already purchased Stage 2...

[LJS5]

Yeah but he already purchased Stage 2...

I was under the impression that Stage 2 purchase include all of stage 1 maps as well. I upgraded from stg 1 -> 2 so not 100% sure.
Just throwing it out there if it's available, OP can just flash the Stage 1 E85 map for maximum gains while retaining stock sound.

[elijahallen]

I was under the impression that Stage 2 purchase include all of stage 1 maps as well. I upgraded from stg 1 -> 2 so not 100% sure.
Just throwing it out there if it's available, OP can just flash the Stage 1 E85 map for maximum gains while retaining stock sound.

Thanks for the info, do you have a link for the exhaust valve controller you are using?

[LJS5]

Thanks for the info, do you have a link for the exhaust valve controller you are using?

https://europrice.us/controller-pack...-exhaust-valve

[Gamil]

Will any mid-pipes void the warranty ?

[jl87]

Will any mid-pipes void the warranty ?

It's up to your dealer. Only way to know for sure is to ask them about it. Some will care and some won't.

[Jeff_Jeske]

As for the power of S1 over S2.... that will vary from tuner to tuner but I can tell you that there are nice gains to be had over the UNI S1 with the UNI S2 tune. The online documentation makes it look like a difference of only 20HP but that isn't reality. That restrictive primary cat sitting just aft of the stock turbo (which is being run at 100%) in the stock downpipe is not only a bottleneck for airflow but also a device that creates back-pressure as well extreme heat in an unwanted location. It is not optimal for performance. The down stream secondary cats in the midpipes are more free-flowing and thus are actually the last restriction would worry about. Be advised aftermarket midpipes provide no performance benefit on their own. However, some claim the car gets 10% louder and other claim that removing the secondary cats actually reduced the crackles.

A catless downpipe does have some downsides, it will be much louder (some may like this), you will hear that notorious wastegate rattle that sounds like a major exhaust leak (Seriously sounds like your car is a POS) and on pump gas you will smell exhaust fumes especially with any tune that leverages injector overrun to provide those attention starved folks pops and bangs.

From what I can tell the gap between S1 and S2 broadens as the weather gets cooler. Uncorking the exhaust makes a huge difference when you can actually move more air (airflow). You should take a look at the 1/4 mile database and review the MPH differences between S1 and S2 cars. Yes there are supporting mods, weight and weather differences but you can clearly see the differences.

Before I purchased the car I was 100% sold on going catless but that was until I heard the WG rattle. I just couldn't deal with that on a daily basis. This knowing there is more than likely 30whp on the table by going S2.

[Chris F]

I put the Uni midpipes on yesterday. Stage 1+ tune with Iroz intercooler. I would say 20-30% louder with no change in tone. I'm very much liking it; still quiet in comfort mode but in dynamic and sport it's like turning up the volume a notch or two on your favorite song. Pops on downshift seem about the same but you can hear more of it now so perceptually it's an increase to me.

[Jeff_Jeske]

If you want to know what wheel horsepower is for a UNI S2 E85 car below is a dyno of the lapping day (dialed back) tune, the standard tune and the standard tune with the stock intake box disconnected meaning no filter.

[mahmutRS3]

Do i have to get mid pipes from a company? Why cant i just go to a exhaust shop and have them cut off the secondary cat and weld a pipe in?

Is there any difference?


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[elijahallen]

Do i have to get mid pipes from a company? Why cant i just go to a exhaust shop and have them cut off the secondary cat and weld a pipe in?

Is there any difference?


Sent from my iPhone using Audizine

Its illegal so most shops will not do it.

[TheContrarian]

Do i have to get mid pipes from a company? Why cant i just go to a exhaust shop and have them cut off the secondary cat and weld a pipe in?

Is there any difference?


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Reversibility is a nice feature.

[tateltot]

I put the Uni midpipes on yesterday. Stage 1+ tune with Iroz intercooler. I would say 20-30% louder with no change in tone. I'm very much liking it; still quiet in comfort mode but in dynamic and sport it's like turning up the volume a notch or two on your favorite song. Pops on downshift seem about the same but you can hear more of it now so perceptually it's an increase to me.

This is my experience as well.

[shifu22]

Midpipe and downpipe makes the car sound amazing! It’s something you should definitely do. I’ve done it and I have had no issue with warranty.


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[HHughes1]

Here is a short clip of my TTRS with going by at about 125mph WOT with cat less midpipes.

https://www.youtube.com/watch?v=JWFJ5qM0F6s

[Gamil]

Just installed OEM midpipes, that's really a nice sound !
And still quiet in D mode.
Dealer told me I might get a check engine light at some point, due to lack of cat. Anyone got that ?

[jl87]

Just installed OEM midpipes, that's really a nice sound !
And still quiet in D mode.
Dealer told me I might get a check engine light at some point, due to lack of cat. Anyone got that ?

Catless midpipes won't give you a CEL. Downpipe with no cat and no tune will.

[Gamil]

Catless midpipes won't give you a CEL. Downpipe with no cat and no tune will.

Yeah that's what i thought at first before doing it, I was just not expecting that from the dealer ???
Anyway it doesn't really matter now :)

[BetoRS3]

This is my experience as well.

Extremely happy to hear that the Uni midpipes produce good results. I just bought them last night.

[xliv]

Midpipe and downpipe makes the car sound amazing! It’s something you should definitely do. I’ve done it and I have had no issue with warranty.


Sent from my iPhone using Audizine

Just installed OEM midpipes, that's really a nice sound !
And still quiet in D mode.
Dealer told me I might get a check engine light at some point, due to lack of cat. Anyone got that ?

Lucky your dealers are cool with adding the catless OEM mids

Spoke to my dealer today and he basically said they're not sure if they'll do the mod and even if they do it could void warranty

I asked how an Audi OEM part could void warranty

His reply: It's not original for NA vehicles and therefore may not coordinate with the "NA tune"

[Gamil]

Lucky your dealers are cool with adding the catless OEM mids

Spoke to my dealer today and he basically said they're not sure if they'll do the mod and even if they do it could void warranty

I asked how an Audi OEM part could void warranty

His reply: It's not original for NA vehicles and therefore may not coordinate with the "NA tune"

yeah indeed, I was lucky not getting this argument... I just showed them the bill from the Audi dealer in Germany, and they installed without question. On the work order it is written "OEM Germany parts provided by the customer".

[Jeff_Jeske]

You can always buy someone's catted mids and smash the honeycomb out with a pipe. Then you would have catless mids with a 100% OEM appearance.

It's too bad catless mids don't actually recover any horsepower.

[xliv]

You can always buy someone's catted mids and smash the honeycomb out with a pipe. Then you would have catless mids with a 100% OEM appearance.

It's too bad catless mids don't actually recover any horsepower.

Good idea as they would likely never check.

Unfortunately got a confirmation from my dealer today that they won't swap out the catted mids as they haven't done it before and don't want to risk voiding warranty

Now speaking to Audi Canada to have them coordinate with the dealership to establish whether or not this swap actually voids warranty... Again the argument I'm making is they're both genuine Audi parts that don't materially change the flow, back pressure, or throw any codes so one would expect the warranty to remain intact