Performance Gains with Catted UEL Headers on Kouki ('17+) 86
 

I have a 2017 Toyota 86 and purchased a set of catted FT86 Speedway UEL headers with the thought that they would slightly increase hp like on zenki models. After doing some research, I discovered that the headers provide negligible gains to hp on kouki models at the very best. So now here I am having had the headers coated with Swain Tech's white lightning and just before installing them, wondering whether I should just resell them.

I'm guessing the increased performance gains amounts to 3 hp at most because of the fewer cells in the cat? Does anyone have any dyno results from catted headers on the kouki models? Besides performance, other factors that I'm considering in making my decision are noise, CEL, and the effects of increased engine bay heat.

Noise: Rumble is great but I don't want my car obnoxiously loud. I already have a TRD catback exhaust and worry about droning.

CEL: Seems like the cat does not guarantee it won't appear, and in NY inspections are required annually.

Engine bay heat: The headers have been coated with a pretty good ceramic coating but they still won't be as cool as what the heat shield on the stock headers provide. I planned on putting heat barrier tape on the oil pan, but I still worry about the effects down the line.

What do you guys think?

I don't understand why they would make that much less power on a refresh car when the refresh only added ~5hp in the first place?

Unless you are talking about no tune, in which case yeah I don't believe headers are worth it.

Did you get a tune? Also FI is the best option for power on this platform which have been a known thing from your research.

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I planned on getting a stage 2 OFT tune once they were installed. Now, I'm guessing I could get comparable or even better performance gains by staying with the stock headers and going with a stage 2+ OFT tune with E85. Would a stage 2 tune work with stock headers since they were upgraded in the '17+ models?

I'm not interested in FI because of reliability issues down the road.

without a tune, gains are neglibible also because pre-restyling oem tunes had poor fueling correction during open loop
So the car would run leaner with aftermarket headers netting some perceivable gains
Restyling US tunes have more fueling correction also in open loop so runs richer
You totally need a tune for them to perform

E85 will make more power than header with tune

I have a 2018 with JDL Catted Headers and I can tell you a tune is absolutely needed if you want any difference in gains.



Noise: If you want to keep it down, even with a catted header, I recommend keeping the stock Front Pipe. Or getting a double resonated one, like an HKS one. I have one and it is great.



Heat: The ceramic coating helps in this department, I haven't noticed any increase in bay area or the transmission. Adding wrap on top o the coating could only detriment your coating as even if it helps against rust and other contaminants, wrap accumulates dust and water. I've never seen cases of heat-soak by those who have ceramic coated headers and decide not to wrap them.



I've put about 30K miles on my headers and I can report zero issues. Definitely get a tune, or even a custom one for OFT. Without a tune, a CEL will show up, eventually. Want more power? E85. Get custom tune for that too.

Thanks for the info.

I have the catted FT86 Speedway UEL headers on my 2020 along with a custom OFT Tune.

I did not do a before/after dyno so I couldn't tell you what the horsepower or torque gain was. But I can say that the impact on the torque dip alone was worth the cost. I also saw about a 4% improvement in lap times on a track I am very experienced at. So I feel comfortable attributing most of it to the power gain rather than me gaining experience.

That said, I'm at an elevation of over 5000 ft, meaning I start off with a good 15% loss in power. So it could be that a small improvement is more noticable to me.

Bottom line is don't be expecting an earthshattering improvement.