Planet-9

991 C4S Performance Upgrades?

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Discussion summary

YOUR RESEARCH991 C4S Performance Upgrades?

Leading reported evidence

Use fabspeed

Performed · outcome unconfirmed

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.

Discussions that performed work without a confirmed outcome: 1

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Performed · outcome unconfirmed
I have heard great things about Soul, but have used Fabspeed for years so it'd be hard to switch at this point.
Original post Read captured discussion
991 C4S Performance Upgrades?

Frequently discussed work

Replace c4s

No successful repair reported for this finding.

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Reported fixes: 0
Unsuccessful attempts: 1
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Discussions that contain suggestions: 1

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Suggestion
This is off the track but I have questions about tire size changes for a C4S.
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991 C4S Performance Upgrades?

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Leading evidence: 'Use fabspeed' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace c4s' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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1 matching discussions · 5 captured posts examined · 1 partial discussions

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Replace c4s

Suggestion or failed attempt

No successful repair reported for this finding.

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Reported fixes: 0
Unsuccessful attempts: 1
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Discussions that contain suggestions: 1

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Suggestion
This is off the track but I have questions about tire size changes for a C4S.
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991 C4S Performance Upgrades?

Use soul exhaust

Suggestion or failed attempt

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

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Suggestion
Typically we use Soul exhaust but either way you'll get good results.
Original post Read captured discussion
991 C4S Performance Upgrades?

Frequently discussed actions (3)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Replace c4s

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion
This is off the track but I have questions about tire size changes for a C4S.
Original post Read captured discussion
991 C4S Performance Upgrades?

Use fabspeed

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that performed work without a confirmed outcome: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed
I have heard great things about Soul, but have used Fabspeed for years so it'd be hard to switch at this point.
Original post Read captured discussion
991 C4S Performance Upgrades?

Use soul exhaust

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion
Typically we use Soul exhaust but either way you'll get good results.
Original post Read captured discussion
991 C4S Performance Upgrades?

Coverage and how to read this overview

Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.

5 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

Planet-9: 1 discussions

0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.

1 acknowledgements have no verified action link; they do not establish a repair result.

Outcome without a verified action link
One guy on youtube dynos before and after install with no difference.
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Generation: 20261027T035758Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1Original post

Hey fellow Porschefiles! I am adding a Fabspeed supersport x-pipe exhaust system to my C4S and wondered about other performance-related mods. I'm interested in your thoughts/experiences related to ANY or ALL of the following: 1. Cold Air Intake : Is there really a noticeable benefit to a CAI unit? I like AFE Black series, but don't want to go to the trouble if it makes little to no difference. There doesn't seem to be much of diff (other than appearance) between the AFE and stock. I'm wondering if simply upgrading to high-flow BMC F1 filters would be just as good. 2. IPD Plenum : I know IPD boasts a noticeable diff in wHP with install, but I've been doing some reading and I'm really not sure if it's all that noticeable. One guy on youtube dynos before and after install with no difference. Also wondering if the new exhaust will work to increase the effectiveness of the IPD sense it will "exhale" much more efficiently, thus enhancing the need for for greater "inhale" capacity. Thoughts? 3. COBB Tuning : I don't think there's any question about whether a COBB tune would increase performance. I'm quite certain it will. My question is, does a tune ultimately shorten the life of an engine? Can't seem to find a good answer on this. 4. Other performance mods : Are there other performance mods I'm missing? Thanks for your help! Ttenneb

POST 2Original post

The BMC filters, IPD Plenum and COBB Accessport are all excellent mods that we sell. Typically we use Soul exhaust but either way you'll get good results. Also we're a COBB Pro-tuner so we would be happy to work with you to optimize the tune. These motors respond well to headers too. Just depends how far you want to go with the upgrades. Here's a GT4 with Soul catted headers, Soul exhaust and BMC filters with our Pro-tune: Picked up close to 40hp IIRC. Let me know if you have any questions.

POST 3Original post

Thanks Joshua! Great video and incredible sound! I have heard great things about Soul, but have used Fabspeed for years so it'd be hard to switch at this point. Not quite a GT4 , but I had a Cayman S which I loved... I did some more research on the CAI and learned there isn't a lot of benefit to it in the 991. I also called Fabspeed and asked why they discontinued their CAI, to which they replied the same. BMC F1 filters are all I need.

POST 4Original post

I don't think you'll be disappointed either way. If you need a hand or have any questions please don't hesitate to ask.

POST 5Original post

This is off the track but I have questions about tire size changes for a C4S. Can someone point me in the right direction??Will I get an error code with a certain overall circumference difference between the front and rears there is a slight difference between 305/30 and 245/35 wonder what the allowance is and were does it begin to cause problems??

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