9 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHMuffler Question 997.1 to 996
Leading reported evidence
Install tubi 997s headers
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that performed work without a confirmed outcome
1
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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've installed Tubi 997S headers on my 2002 c4S with no problems
Leading evidence: 'Install tubi 997s headers' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'impetus' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Install tubi 997s headers' (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.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
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Discussions that suspect a cause
1
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Suspected cause
I suspect the impetus for the 997 header new look was to use fewer part types.
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Discussions that contain suggestions
1
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Suggestion
An analogy would be replacing your cats with straight pipes which has been known, in some cases, to reduce engine output.
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 contain suggestions
1
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Suggestion
I suspect the impetus for the 997 header new look was to use fewer part types.
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 contain suggestions
1
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Suggestion
My primaries are dented so I'm looking for a replacement and prefer using stock parts.
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.
9 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T013556Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I have been pondering that swap ... 997S headers do apparently bolt on in place of the 996 headers. My primaries are dented so I'm looking for a replacement and prefer using stock parts. But the design of the 997S headers is not too pretty as compared with the 996 headers ... I wonder if these flow better?. Some Rennlisters have used them though, apparently with good results.
Pictures to illustrate... 996 headers shown first.
Cheers,
Michael
2004 C4S
It's your car so do as you please but I would stick with OEM exhaust. The Porsche OEM exhaust system is one of the best designed in the world. The OEM parts are of the highest quality. I researched the exhaust systems for 996 extensively and see no compelling evidence to "upgrade" to anything else. Most systems advertised as "upgrades" are in reality downgrades. YMMV.
My friend (Nissan GTR Approved tech) told me that for a better flow, all the tubing must be the same length so the pressure is identical when they merge, seems the case with the 997s headers.
997 headers are for 3.6L engines, yours is a 3.4L. The 997 headers may flow too freely in a 3.4L application. Horsepower may not be affected much but torque needs some flow resistance to be maximized. An analogy would be replacing your cats with straight pipes which has been known, in some cases, to reduce engine output. So while the header may fit physically, it may not be an improvement.
I suspect the impetus for the 997 header new look was to use fewer part types. A pair of 996 headers has 6 different pipes welded to the flanges. The 997 design uses 3 and 2 of them are the same diameter and bend but with the opposite angle at the merge.
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