Planet-9

DIY OEM Header DECAT...(sorry if it has been discussed)

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3 captured repliesPartial discussion capture · Source accounts, not a confirmed diagnosis

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YOUR RESEARCHDIY OEM Header DECAT...(sorry if it has been discussed)

Leading reported evidence

Run bit around the perimeter

Performed · outcome unconfirmed

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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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

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 cut and "X" pattern in the Cat from the exit side (obviously), then ran the bit around the perimeter.
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DIY OEM Header DECAT...(sorry if it has been discussed)

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Leading evidence: 'Run bit around the perimeter' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Run bit around the perimeter' (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 · 3 captured posts examined · 1 partial discussions

Compare 2 other evidence results

Use copper spray gasket "thin coat"

Performed · outcome unconfirmed

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
So i installed them and reused the OEM manifold to head gaskets (cleaned them up and used copper spray gasket "thin coat" and used new OEM manifold to muffler gaskets.
Original post Read captured discussion
DIY OEM Header DECAT...(sorry if it has been discussed)

Use oem manifold

Performed · outcome unconfirmed

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
So i installed them and reused the OEM manifold to head gaskets (cleaned them up and used copper spray gasket "thin coat" and used new OEM manifold to muffler gaskets.
Original post Read captured discussion
DIY OEM Header DECAT...(sorry if it has been discussed)

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.

Run bit around the perimeter

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 cut and "X" pattern in the Cat from the exit side (obviously), then ran the bit around the perimeter.
Original post Read captured discussion
DIY OEM Header DECAT...(sorry if it has been discussed)

Use copper spray gasket "thin coat"

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
So i installed them and reused the OEM manifold to head gaskets (cleaned them up and used copper spray gasket "thin coat" and used new OEM manifold to muffler gaskets.
Original post Read captured discussion
DIY OEM Header DECAT...(sorry if it has been discussed)

Use oem manifold

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
So i installed them and reused the OEM manifold to head gaskets (cleaned them up and used copper spray gasket "thin coat" and used new OEM manifold to muffler gaskets.
Original post Read captured discussion
DIY OEM Header DECAT...(sorry if it has been discussed)

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.

3 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.

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

Generation: 20261026T200546Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1Original post

Hey guys, so... I had a set of Long tube Catless headers on my ( 987.1 S) It sounded mean at higher RPM's but at lower RPM's starting off (manual Trans), it sounded like i had an exhaust leak.. Couple more people said they experienced the same. I removed them on two occasions and no sign of a leak at all. So I decided to take the OEM headers and remove the cats Tools needed: Drill, 1/4 or 3/8 spade drill bit and rubber mallet I cut and "X" pattern in the Cat from the exit side (obviously), then ran the bit around the perimeter. Next hold it with exit side facing down and hit it with the rubber mallet.. Literally took me 5 to 7 min per header... Super easy. So i installed them and reused the OEM manifold to head gaskets (cleaned them up and used copper spray gasket "thin coat" and used new OEM manifold to muffler gaskets. I still get the same "leak" sound so maybe 1/10th as pronounced... Ive listened to a few stock Caymans and they all have that same sound but i think its absorbed by all the cats... So now i have no cats but the chamber that used to hold the Catalytic converter now acts as a resonator and muffles some of the weird exhaust noise. All in all Im sticking with the OEM Catless headers because I fell that The power loss is minimal and the OEM header is a pretty decent design anyway... Oh and it still RIPS at high RPMS.. So sound is not a problem with the OEM headers.. I would recommend this mod for sure and its free!!!!!!!!!!!

POST 2Original post

what longtube headers did you have and do you plan on selling them?

POST 3Original post

Another option is you can cut an opening in the cat. Gut the cat and weld in a few small baffles. Basically turn the cat into a free flowing muffler. A local motorcycle custom shop would have the welding skills and extra stainless steel pipes to create the muffler baffles. Then have it all ceramic coated before installing it.

This is a source reference. Confirm exact model applicability in the original material.