GR Yaris Opinion: Original exhaust and OPF

Onehp

Onehp

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Dec 6, 2021
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The number 1 topic on most car fora is getting a new exhaust. A louder one, better performance, lighter. I've done my share.

Here are my thoughts on the OE exhaust (OPF in second post) and why it's pretty good imho:

Weight
It has two big dampers, two exits and weighs 13kg. That's light. Most aftermarkets will be same or are a lot heavier. A fancy Ti exhaust costing several thousands will save no more than a handfull kg.

Performance
It actually has a descent diameter and no mahoosive backpressure. The performance gains I've seen advertised are a lot less then on other car platforms and not of a magnitude you will actually feel.

Noise
Yes it isn't loud, but it actually does have a voice. And as many have noticed, it actually gets a bit more vocal with miles, I can actually hear it and ticking over on my driveway, it actually resonates through the house. Stock.
And here comes my opinion about picking aftermarket exhaust - many of us are pretty bad at it, myself including. We pick what we like on a vid or from a 2min hearing, crowd pleasing. But once we get the exhaust, several things happen. One, it usually gets louder again with miles. And two, in the reality of actually using the car, the drone starts to grate, that is if the car is more than an occasional fun car. As @JonW points out elsewhere, in e.g. Aus there are an uncanny large amount of people selling their exhausts, a good part citing too loud as the reason.
I've personally 'done' exhausts on 4 cars previously and on every single one I had either sold the car (1) soon after or made the exhaust quieter later on and was happier about it.
Also my very personal opinion, from the exhaust sounds I've heard, the aftermarket sound 'good' but in reality, I want it to sound 'great' if I'm going to bother again. The untouched engine (ese off) actually has a characterful note and enjoying as is...
If you do get one, my advice is to get an approved one for long term enjoyment, for yourself and in contact with authorities (rules vary per country, rules and/or enforcement will only become stricter)

Enjoyment
A bit ironically, an exhaust that doesn't get you noticed instantly allows for more opportunities for driving enjoyment

Optics
Some change exhaust simply because they don't like the tinny exhaust tips. Ok not a massive improvement but painting the inside matte black (hi temp spray paint) helps a bit
20210830_124342.jpg


Or if you really only want the looks, you could just cut the OE tips and put on adjustable clamp aftermarket tips. Or have a good shop weld some on.

Price
For some reason, GR exhausts are like 50% more expensive then on other comparable car models. Go figure.
 
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OPF
All above was about OPF-back systems. Not all countries get OPF. I almost exclusively read in negative terms about OPF's in car forums so therefore I'm gonna write something more about it here, I never got to it in the old place.

Main reason of hate, they steal sound and sap power. The GRY OPF is quite good, doesn't steal much sound apparently and difference in power isn't massive between versions. More on that later, but why OPF?

Silent Gasolinegate?
It suprised me how many people that have a history of not caring one jota about emissions on their cars were genuinely upset with VAG in Dieslegate. Upset about the (industry wide) cheating or about the emissions? Also quite often the same people hate OPF's which is a bit contradictory? Anyhow.

OPF's were silently introduced on the back of dieselgate. No big scandal or anything. No manufacturer had cheated, but from emissions point of view, it is almost a bigger deal. Regulators had missed that measuring soot emissions per weight allowed smaller and therefore much lighter soot produced by DI gasolines (e.g. 10 times smaller => 1000x lighter, iirc they are approx 4x smaller) to pass regulation and studies found these were incredibly harmful. Al kinds of nasty combustion byproducts unique for gasolines (high benzene content, known cancerogenic, that reacts and forms all kinds of shit), many of who we haven't even got a clue how harmful they are, were now getting a transport device (soot, carbon ball) straight into our lugns and tissue. DI creates soot.

Now we all hate cancer and what it does, but it is human nature not to make the direct link with the causes, as we can never pinpoint from where someone got cancer, reality being so complex. So here I'm just gonna say, it is scientifically proven that these emissions cause cancer. And not just lung cancer as one might think, but all kinds of cancer. Plenty of literature on the subject. And that's for the compounds we have studies, the list of the ones we haven't is much longer.

And the OPF cuts these emissions MASSIVELY

Realising that I'm not immortal, the subject of mid-life crisis whenever that actually happens, I feel it is actually very good to have such an entertaining car WITH an OPF.

No DPF woes
Because of the lighter soot and the higher exhaust gas temps, OPF will give much less issues with clogged filters.

Tuning
Well simply put, it is illegal to remove the OPF. If you don't get caught now, you might in the future and fines will only go up.
For race and track cars I personally I fully understand the OPF is in the way of performance. But for cars used as daily transportation, they are good.

Legal power gain is possible with the HJS sports cat and from @Phil1291 initial timing it is almost as affective as a tuning box.
 
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I like the stock exhaust too. I don't really underdstand people who want loud ones. But maybe i'm to old :)
I just changed the tailpipes for optics.
880CDF95-C543-452B-8797-8B22EA18AB8E.jpeg
 
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Good write up, points well made.

The exhausts I kept seeing being sold here in Aus were always low kms, nor more than a few thousand and most were hundreds and only very recently fitted. Seems guys like the idea of the noise but then discover its not needed or wanted.

Ive said elsewhere that as we move on with the adoption of more quiet new cars, especially electric cars, anything noisy will really stand out and while today thats fine as there are lots of noisy vehicles, that probably wont always be the case and could get you more attention than you would want. Personally I live in a noisy city, the Audi/VWs who fart pass my house past midnight annoy me, and lets not get started on the i30N owners who think the rest of the world wants to hear their cars pop and bang... What irks most is that they can switch that off with a button press. Rude.

Also, the OEM exhaust was said at one point to have been looked at by a race or rally team (I forget who) and they said they couldnt make the car any more powerful with another exhaust, only noisier. So while most OEM systems restrict power it seems ours is not only quite light, but also works well. What's not to like...
 
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I run opf delete and none Res back system. Cold start is loud for 20 seconds then it's fine. Revs and pulls better top end of rev range.
 
Interesting that you say that, In Aus we dont have the GPF/OPF. I dont have the ESE switched to 'on' in my car and on start up and at low revs it sounds like a diesel. That will be mostly the noise from the Direct Fuel Injection i would think but perhaps its the exhaust as well as without the GPF there is less to restrict it.

One thing people say is that these cars are 'silent' without an exhaust, thats not really true. They do have noise, especially at revs. With ESE off you can hear induction and exhaust (and BOV) noises, though there is tyre noise as well of course.
 
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Fred said:
You meant you passed the TÜV without OPF and with HJS kat?
Shouldn't be a problem at all...
Click to expand...
Yep. I installed the HJS catalytic converter and threw out the Opf. Went to the MOT(Tüv) and passed. They only thing we had to block one exhaust pipe because the inspector said it was drawing false air.

But the dirty EU has already come up with something new and within the next two years the values and so on are supposed to be read out even better and then no one will be able to get through without a perfect exhaust Cat/Opf.

In the Hyundai forum I even read about some people who can't get through with the original i30n catalytic converter anymore. Yes with the OEM....:). It's going to be a good time. So down with the EU-Brussels bullshit. I'm out of the topic now, I'm just getting really worked up again.
 
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Onehp said:
OPF
All above was about OPF-back systems. Not all countries get OPF. I almost exclusively read in negative terms about OPF's in car forums so therefore I'm gonna write something more about it here, I never got to it in the old place.

Main reason of hate, they steal sound and sap power. The GRY OPF is quite good, doesn't steal much sound apparently and difference in power isn't massive between versions. More on that later, but why OPF?

Silent Gasolinegate?
It suprised me how many people that have a history of not caring one jota about emissions on their cars were genuinely upset with VAG in Dieslegate. Upset about the (industry wide) cheating or about the emissions? Also quite often the same people hate OPF's which is a bit contradictory? Anyhow.

OPF's were silently introduced on the back of dieselgate. No big scandal or anything. No manufacturer had cheated, but from emissions point of view, it is almost a bigger deal. Regulators had missed that measuring soot emissions per weight allowed smaller and therefore much lighter soot produced by DI gasolines (e.g. 10 times smaller => 1000x lighter, iirc they are approx 4x smaller) to pass regulation and studies found these were incredibly harmful. Al kinds of nasty combustion byproducts unique for gasolines (high benzene content, known cancerogenic, that reacts and forms all kinds of shit), many of who we haven't even got a clue how harmful they are, were now getting a transport device (soot, carbon ball) straight into our lugns and tissue. DI creates soot.

Now we all hate cancer and what it does, but it is human nature not to make the direct link with the causes, as we can never pinpoint from where someone got cancer, reality being so complex. So here I'm just gonna say, it is scientifically proven that these emissions cause cancer. And not just lung cancer as one might think, but all kinds of cancer. Plenty of literature on the subject. And that's for the compounds we have studies, the list of the ones we haven't is much longer.

And the OPF cuts these emissions MASSIVELY

Realising that I'm not immortal, the subject of mid-life crisis whenever that actually happens, I feel it is actually very good to have such an entertaining car WITH an OPF.

No DPF woes
Because of the lighter soot and the higher exhaust gas temps, OPF will give much less issues with clogged filters.

Tuning
Well simply put, it is illegal to remove the OPF. If you don't get caught now, you might in the future and fines will only go up.
For race and track cars I personally I fully understand the OPF is in the way of performance. But for cars used as daily transportation, they are good.

Legal power gain is possible with the HJS sports cat and from @Phil1291 initial timing it is almost as affective as a tuning box.
Click to expand...
Do you seriously think the state(s) introduces regulations to protect its citizens?
How about then e.g. with cancer causes from 5G and "vaccines"?
 
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You removed your cat completely?
What the f**k dude....do you really need the extra few horsepower that desparately?
That's pretty damned selfish.
I'm gonna guess you came from a V6 Commodore or AU Falcon masterpiece with punched cats? Do your kids think your mullet looks ghey or do you dress them up as bogans too?
Or maybe you are a finance bro boy wonder who positions themselves above all (and their lungs etc)
 
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SckSqzBngBlo said:
You removed your cat completely?
What the f**k dude....do you really need the extra few horsepower that desparately?
That's pretty damned selfish.
I'm gonna guess you came from a V6 Commodore or AU Falcon masterpiece with punched cats? Do your kids think your mullet looks ghey or do you dress them up as bogans too?
Or maybe you are a finance bro boy wonder who positions themselves above all (and their lungs etc)
Click to expand...
Blow me 😘
 
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Great write up! I daily a GR Yaris and I had a resonated exhaust with two twin rear silencers and a resonated centre pipe but even that was too loud for me since I drive around in town. I ended up with a Fujitsubo which isn’t louder than the original exhaust whilst pottering in town but has a much nicer, sportier tone than the OEM one when giving it some beans. Regarding the GPF, I completely agree with you - a GPF delete may sound nicer now but in the UK at least, with the ever changing rules and regulations to do with emissions, it could well be the case that you’d have to revert back to the original GPF in the future. Again, great post!
 
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Well had a little exchange on OPF removal with @Sekred in a personal build thread that derailed. Here the two basic facts I want to save for posterity as it almost never gets mentioned:

- Car tailpipe emissions in developed countries like UK and nordics cause ballpark 10x as many premature deaths as traffic accidents. That's a lot...

- Removing a GPF increases particle emissions roughly tenfold. That's not a little delta.


And my personal comment:
This is scientifically only relevant for cars used daily in build-up areas, doesn't really matter for cars used on occasional countryside runs and trackdays. I'm in driving for fun, and that has a cost, but at some point the sacrifice maybe doesn't outweigh the benefit. For a daily driven car in upbuilt areas, removing a GPF is imho a bit of a shame when it already was there....

With way too many family and friends under 50 getting cancer, yes I make a link there even if it's impossible to prove direct causation....
 
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