Tune revision needed for Kooks long tube headers?

[Da Pony]

2025 Mustang GT 6MT - Lund says no revision needed for Kooks 1-7/8" long tubes with green cats?


I'm currently running a Lund tune on my 2025 Mustang GT manual. I just ordered Kooks KSH1151H432 1-7/8" long-tube headers with green cats and asked Lund if I needed a revision before installation.


Their response was:


"No revision needed for headers sir. Bolt on and go."


Has anyone else with a 2024-2025 S650 GT received the same guidance from Lund?


Specifically:

1. Is Lund saying the existing tune already has enough fueling and airflow adjustment to handle long tubes?
2. Will there be any horsepower left on the table without a dedicated header revision?
3. Did anyone see measurable gains after requesting a header-specific revision anyway?
4. Any drivability, fuel trim, or cold-start differences after installing Kooks long tubes with green cats on an existing Lund tune?

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[Nolasalt]

I would trust what Lund told you over any response you get here.

 

[robvas]

 

[Da Pony]

I would trust what Lund told you over any response you get here.

I may be reading too much into the response, but because Lund's reply was so brief, it left me with a few questions. When they said no revision was needed, I wasn't sure whether they meant there was no additional performance to be gained from a header-specific revision or simply that the car would run safely and correctly without one. Has anyone seen gains from a header-specific revision after installing long tubes?

 

[robvas]

header-specific revision

What do you think they could possibly change to increase performance that isn't there on the non-header tune?

You're flowing a couple % more air through your engine after you put headers on it. Your car will adjust the tiny bit more of fuel on it's own. Other than that...

 

[Ninjak]

Headers will allow more volume of air to flow freely out of the system. It will also change the note of the vehicle. From my experience, tuning around headers has not been a factor.

 

[ZXMustang]

They are right. Nothing to change on these MAP based cars. On the MAF cars you might need to adjust fueling a tad if you are actually flowing more in because you are getting more out faster, but not with the s650. These cars dont care what intake or exhaust you are running. Now if you locked out the IMRCs or got a CJ intake manifold, there is work to be done. Also if you get catless headers, but most wont make "those" adjustments anymore.

 

[Da Pony]

Thank you for all the responses.

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