Questions about High Flow Cats
12-04-2018, 09:59 PM
#1
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Questions about High Flow Cats
Hey guys, I own a 991.2 T and I am looking into 200 cell HF cats to improve the sound of my beloved Porsche. As such, I have a few questions.
1. Will HF cats affect my warranty? If so, How?
2. Do I need to tune my ECU or use O2 spacers or anything like that to avoid CELs? Or are the cats just "bolt on and go"?
3. Can I pass inspections with HF cats? I'm from MA if that helps.
4. Does anyone have a good sound clip or something that can accurately illustrate how a 991.2 sounds with HF cats and PSE?
Thanks to everyone in advance!
1. Will HF cats affect my warranty? If so, How?
2. Do I need to tune my ECU or use O2 spacers or anything like that to avoid CELs? Or are the cats just "bolt on and go"?
3. Can I pass inspections with HF cats? I'm from MA if that helps.
4. Does anyone have a good sound clip or something that can accurately illustrate how a 991.2 sounds with HF cats and PSE?
Thanks to everyone in advance!
12-05-2018, 12:06 AM
#2
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1. It depends on the dealer but it would hard for them to prove something broke with just a 200 cell cat.
2. No, and for example Soul even states in that no CELs with their cats and no one is getting them.
3. Not sure but I am sure you can find out; however, I don't think the car will fail with them. They look stock and I am sure you can have Soul make them without any logo or name.
4. There are several online and Soul and others have them on their web sites. You can also Google 991.2 high flow cats and you will find many on YouTube, or search this forum for some.
2. No, and for example Soul even states in that no CELs with their cats and no one is getting them.
3. Not sure but I am sure you can find out; however, I don't think the car will fail with them. They look stock and I am sure you can have Soul make them without any logo or name.
4. There are several online and Soul and others have them on their web sites. You can also Google 991.2 high flow cats and you will find many on YouTube, or search this forum for some.
12-05-2018, 02:33 AM
#3
Burning Brakes
I just had 200 cell SOUL cats plus BMC air filter installed today with no issues/no CEL. The sound is just right to my ears. It’s definitely noticeable and an improvement from stock cats, especially with PSE engaged. Sorry, I don’t have sound clips. Just YouTube it. In California, it will apparently pass smog since they only hook it up to the OBD port but may fail the sniff test. Warranties and inspections are always subjective, and will vary from different dealerships. Hate to say it but sometimes you gotta pay to play.
12-05-2018, 05:23 AM
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Last edited by worf928; 12-05-2018 at 09:40 AM.
12-05-2018, 07:19 AM
#5
Another question - I have a 991.1 CS with PSE. What performance gains would be expected from high flow cats? Also, does the car need to be tuned (e.g., Cobb) to take advantage of the high flow cats?
I’m new to the forum and if I should start a separate thread, let me know.
I’m new to the forum and if I should start a separate thread, let me know.
12-05-2018, 11:36 AM
#6
Replacing a exhaust part or intake will give a some amount of additional air flow, If any. To make the ecu recognize and use that information you need a upgraded ecu program. Get one that is capable of recognizing the mods you have done. Usually the ecu program alone makes a big difference in hp & responsiveness
12-05-2018, 11:45 AM
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Replacing a exhaust part or intake will give a some amount of additional air flow, If any. To make the ecu recognize and use that information you need a upgraded ecu program. Get one that is capable of recognizing the mods you have done. Usually the ecu program alone makes a big difference in hp & responsiveness
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12-05-2018, 01:18 PM
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12-05-2018, 02:11 PM
#10
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Alright guys, thanks for all the answers. I looked around and found a few videos comparing the before and after sound, and from what I can tell there seems to be more low end growl when revving the engine at idle. It's been harder to find clips of the car moving at high revs.
Can anyone tell me how SOUL cats sound when at high rpms? Is it reminiscent of old air-cooled engines in any way?
Basically, I want my T to sound like this (0:30 - 0:38)
:
Can anyone tell me how SOUL cats sound when at high rpms? Is it reminiscent of old air-cooled engines in any way?
Basically, I want my T to sound like this (0:30 - 0:38)
:
12-05-2018, 09:08 PM
#11
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PM sent, thank for the consideration. And thank all you guys for the kind words 
__________________
SOUL PERFORMANCE PRODUCTS
Quality Exhaust Solutions, Fair Pricing, and Outstanding Service
John Gaydos- Owner, Performance Specialist
Cell - (484) 883-6197
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jwheel@soulpp.com
SOUL PERFORMANCE PRODUCTS
Quality Exhaust Solutions, Fair Pricing, and Outstanding Service
John Gaydos- Owner, Performance Specialist
Cell - (484) 883-6197
johng@soulpp.com
Jon Wheel - Marketing Manager
jwheel@soulpp.com
12-05-2018, 09:12 PM
#12
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Another question - I have a 991.1 CS with PSE. What performance gains would be expected from high flow cats? Also, does the car need to be tuned (e.g., Cobb) to take advantage of the high flow cats?
I’m new to the forum and if I should start a separate thread, let me know.
I’m new to the forum and if I should start a separate thread, let me know.
I've built a lot of the 991.1s, and with a properly made set of "street headers" with high flow cats you should be able to make some solid gains. We're actually in the midst of developing these for the 991.1 and they should be ready to release in the next couple months. We'll knock them out of the park don't you worry. And yes, the 991.1 does like tuning by itself, and with some high flow headers the gains will be that much better.
12-06-2018, 09:55 AM
#13
Former Vendor
For number 3 are you only referring to visual inspection or actual emissions testing? They are very different.
Soul, do you have any info in 5-gas data from OEM to your cats? I know there are stark difference going from OEM to an aftermarket 'emissions compliant' cat, and again to a full-on race cat. Curious where you guys fall on that spectrum.
Soul, do you have any info in 5-gas data from OEM to your cats? I know there are stark difference going from OEM to an aftermarket 'emissions compliant' cat, and again to a full-on race cat. Curious where you guys fall on that spectrum.
12-06-2018, 10:18 AM
#14
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For number 3 are you only referring to visual inspection or actual emissions testing? They are very different.
Soul, do you have any info in 5-gas data from OEM to your cats? I know there are stark difference going from OEM to an aftermarket 'emissions compliant' cat, and again to a full-on race cat. Curious where you guys fall on that spectrum.
Soul, do you have any info in 5-gas data from OEM to your cats? I know there are stark difference going from OEM to an aftermarket 'emissions compliant' cat, and again to a full-on race cat. Curious where you guys fall on that spectrum.
12-06-2018, 01:41 PM
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MA’s system is to use an ODB-II reader. As long as there are no emissions or engine codes you pass...
... unless your car sounds like it has been ‘modified.’
As long as your car sounds reasonably normal within the earshot of the technician there will be no issue.
If you slide into the parking lot at 4k rpm with a free-flow exhaust expect a visual inspection.
If the car, at idle, rattles windows... you better know of an inspection station without windows.