exhaust and headers upgrade

[86MLR]

Originally Posted by jflogerzi

Even with the cat punched out... It still cut down on noise? I am very curious about this

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If your talking about between the punched out OEM header and the Tomei than yes.

With the only difference being the Tomei header.

Cold start is still loud with the punched out cat, but it was ridiculously loud with the Tomei.

My cold start should hopefully get muffled down in a couple of weeks, I've been told a turbo is great for muffling exhaust noise......

[jflogerzi]

Originally Posted by 86MLR

If your talking about between the punched out OEM header and the Tomei than yes.

With the only difference being the Tomei header.

Cold start is still loud with the punched out cat, but it was ridiculously loud with the Tomei.

My cold start should hopefully get muffled down in a couple of weeks, I've been told a turbo is great for muffling exhaust noise......

Hum... I am debating going back to stock headers. Was there a big difference between stock headers with CAT and no cat noise wise. I am tried of the loud driving noise with Windows rolled up. Trying to source a cheap 2017+ OEM header... But I still have my 2013 stock header I could try punching out the stock cat

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[86MLR]

Originally Posted by jflogerzi

Hum... I am debating going back to stock headers. Was there a big difference between stock headers with CAT and no cat noise wise. I am tried of the loud driving noise with Windows rolled up. Trying to source a cheap 2017+ OEM header... But I still have my 2013 stock header I could try punching out the stock cat

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I find the OEM header with punched cat fine, and I'm old and grumpy.

It is louder, but not that much.

I say go for it, then get a tune and post results.

[new2subaru]

Originally Posted by jflogerzi

Hum... I am debating going back to stock headers. Was there a big difference between stock headers with CAT and no cat noise wise. I am tried of the loud driving noise with Windows rolled up. Trying to source a cheap 2017+ OEM header... But I still have my 2013 stock header I could try punching out the stock cat

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Are you talking about noise from the headers/engine compartment?

[jflogerzi]

Originally Posted by new2subaru

Are you talking about noise from the headers/engine compartment?

Both. I am also looking to replace my current MXP SP current catback with with a Fujitsubo Authorize S axleback. I think this will be the perfect combo. With the supercharger I have destroyed the TQ dip and thus would only loose 10whp which is not a big deal. Will first see what the exhaust is like with just the SP and 2017+ header with a cat. Then maybe punch out the cat in my 2013 header for grins and compare

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[twr7cx]

Originally Posted by 86MLR

Punched out 17+ OEM header, 2.5" overpipe, 2.5" resonated front pipe, 2.5" cat back

Then

Replaced cat back to OEM with zero change to performance...

Then

Replaced 17+ punched out header with Tomei UEL header, zero performance gain...

For NA The OEM system flows great once the restrictions are removed.

So based on that above, your saying there’s no performance gains, and therefore likely no unnecessary restrictions in the stock headers and cat converter of the OEM system of 2017+ vehicles.
What about the rest the of the exhaust system post the converter? Has any testing been done to see if the aftermarket sports systems actually reduce any restriction and provide gains? Did you dyno test your 2.5” system against an OEM setup? Is the cat back different on 2017+ models compared to earlier models?

According to DSPORTS’s article < https://dsportmag.com/the-tech/scion...programed-ecu/ >, quoted below, the ECU limits further power gain to no more than an additional 5% of the stock power. Do you think that had any effect on your dyno testing without returning for each of the changes?

The 5-Percent Rule

Because the ECU in the Scion FR-S has tables built in that essentially limit the amount of additional power that can be made, dyno testing bolt-on products on the vehicle proved extremely challenging. Based on over 250 dyno runs that we conducted, we found that the ECU seems to only allow performance gains on the order of about 5.0 percent. Adding the additional components to allow more additional power production with the factory-programmed ECU still only delivers that 5.0 percent gain.

1+1 = 1

Let’s say that you have an intake that adds about 5.0-percent more power when installed on a stock vehicle. Now, let’s say you have an exhaust system that adds about 5.0 percent of power on a stock vehicle. While you shouldn’t expect to get a 10.0-pecent gain from the two, it’s realistic to expect to see a performance gain with both items in the realm of 6.0- to-9.0 percent. Yet, the factory- programmed Scion FR-S ECU says 1+1 = 1. We confirmed the severity of the 5.0-percent rule when we found that the Scion FR-S simply didn’t gain any additional power when an aftermarket exhaust was added after the addition of an aftermarket intake system. On DSPORT’s DynoJet 424xLC Linx dyno, the number that could never be exceeded was about 182 wheel horsepower. Stock horsepower figures checked in between 173 and 176 horsepower when tested on different days.

[86MLR]

Originally Posted by twr7cx

So based on that above, your saying there’s no performance gains, and therefore likely no unnecessary restrictions in the stock headers and cat converter of the OEM system of 2017+ vehicles.the catalytic converter is the restriction in the OEM header, tube size and lenght is pretty good
What about the rest the of the exhaust system post the converter? Has any testing been done to see if the aftermarket sports systems actually reduce any restriction and provide gains? the OEM overpipe wasn't tested, but, it was fairly rubbish looking, a 2.5" was only $100, the only restriction in the OEM front pipe was the 2nd cat when NADid you dyno test your 2.5” system against an OEM setup? Is the cat back different on 2017+ models compared to earlier models? haven't used a pre 17 catback,

According to DSPORTS’s article < https://dsportmag.com/the-tech/scion...programed-ecu/ >, quoted below, the ECU limits further power gain to no more than an additional 5% of the stock power. Do you think that had any effect on your dyno testing without returning for each of the changes?

Sounds about right, although, adding modifications without tuning will never give best results

95% of power gains, after removing the cats, are in the tuning

Currently the car is running a AVO turbo at 8psi, still using the same 2.5" overpipe, but, have swapped out the front pipe to a SME 2.5" resonated mated to the OEM catback, car made 205kw??? dynopowers

In conclusion, the OEM catback seems to flow fine up to 270ish hp, the only real reason to change it would be for noise at these power levels

Opinions may vary

Edit: your in Hobart, if you have a mate or family in Sydney you can do some testing your self for the cost of a 10 pack > https://www.ft86club.com/forums/showthread.php?t=136760

Free Mishimoto intake pipe with every Header swapped......

[twr7cx]

Originally Posted by 86MLR

[COLOR="red"]the catalytic converter is the restriction in the OEM header, tube size and lenght is pretty good

Ah right. Sorry, but I misinterpreted your statement below and thought you meant you replaced it back to the stock cat converter, not the stock cat back exhaust system:

Originally Posted by 86MLR

Replaced cat back to OEM with zero change to performance, knocked down the noise a bit

I read it as 'replaced cat [converter] back to OEM...' not 'replaced cat back [exhaust] to OEM...'.