Headers Only

[Offboost]

I am curious if anyone has done just long tube headers and green cats WITHOUT a TUNE or intake?

I realize that a tune will maximize everything but just curious about the results, I can only find threads with intakes, tunes and E85.

Also curious why people who have tunes can install headers and not need retune but most say headers on a stock Ecu require a tune. If the air mass sensor meaures x amount of airflow I think the fuel system can richen up or lean out enough to compendate unless the wide open table is fixed and wont compensate.

I also know 0/2 sensor locations are now different and may give slightly inacurate readings.

Not looking to debate tunes just really curious if anyone has actually done this besides Kooks or American racing.

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[nastang87xx]

Headers don't REQUIRE a tune per say but if you don't, you'll throw a catalyst inefficiency CEL which won't hurt anything but you'll still have the CEL. If a car has wideband front O2 sensors you're fine as in you won't hurt anything but it certainly helps performance. Due to the headers allowing more effective evacuation of exhaust gases, theoretically, your mixture should be running lean (unburned fuel has a chance to escape faster with less back pressure).

 

[superman07]

VOODOO ran lean on Lund ff tune and ARH with x pipe to stock mufflers at WOT, needed to have fuel added post datalogs running 100 octane. E85 would have likely been worse. I believe the ARH is a superior header based on the few dynos out there but its hardly conclusive.

That would suggest to me the above comment is right on, it will be a bit lean.

 

[Offboost]

Thanks for the responses but it seems no one has done it without a tune and using cats. Like was mentioned Voodoo already had a Lund tune. I also think the green cats will most likely not set a check engine light but am not sure.

 

[nastang87xx]

Thanks for the responses but it seems no one has done it without a tune and using cats. Like was mentioned Voodoo already had a Lund tune. I also think the green cats will most likely not set a check engine light but am not sure.

No, they're supposed to be pretty damn good from my understanding but DAMN are they expensive.

 

[Offboost]

No, they're supposed to be pretty damn good from my understanding but DAMN are they expensive.

Yes they are and will probably hurt a few ponies as well.

Les

 

[Mike02z]

As noted above, you can run headers without a tune. You'll get a CEL due to the rear O2's being moved back. They won't get hot enough and will eventually throw a CEL. There are 3 issue with this in my opinion.

1) If you have to get an emissions test, you will fail. If you clear the code it will not have enough history and they will tell you to come back once more miles are on it.

2)The other more serious concern is without a tune, it may lean out the fuel/air too much. That will cause detenation and eventually you'll say bye bye to the motor.

3.) If you live in CA or NJ forget headers or you will fail with LT headers. Anything that moves the position of the stock cats makes the car not public road legal. Many states could care less but at least those 2 are killers when it comes to LT headers.

Opinions vary but I would not do headers without a tune. Simply not enough gain stock to justify the cost. I would not do a tune as that will impact your power train warranty.

I have done headers on many cars but for warranty reasons, I'm not doing anything that might jeopardize my PT warranty on this car.

 

[Offboost]

As noted above, you can run headers without a tune. You'll get a CEL due to the rear O2's being moved back. They won't get hot enough and will eventually throw a CEL. There are 3 issue with this in my opinion.

1) If you have to get an emissions test, you will fail. If you clear the code it will not have enough history and they will tell you to come back once more miles are on it.

2)The other more serious concern is without a tune, it may lean out the fuel/air too much. That will cause detenation and eventually you'll say bye bye to the motor.

3.) If you live in CA or NJ forget headers or you will fail with LT headers. Anything that moves the position of the stock cats makes the car not public road legal. Many states could care less but at least those 2 are killers when it comes to LT headers.

Opinions vary but I would not do headers without a tune. Simply not enough gain stock to justify the cost. I would not do a tune as that will impact your power train warranty.

I have done headers on many cars but for warranty reasons, I'm not doing anything that might jeopardize my PT warranty on this car.

Totally understand what you are saying.

I will most likely order the Kooks and green cats and I will try and get a dyno before and after and confirm air fuel ratio at the time of the dyno and if it is safe and makes power I will not tune it but I certainly plan on verifying the air fuel ratio at WOT. I will not tune it if its safe plus I think this will be good info for everyone to know to see exactly how much the air fuel ration actually changes with headers and green cats along with seeing what the true gains or losses will be.

 

[nastang87xx]

There are also some states that don't allow your rear O2 sensors to be in "Not Ready" status or shown as tuned out such as Virginia. Other states will allow 1 "Not Ready" across the board. It just depends on the state. Either case, removing factory emissions hardware technically is ILLEGAL period, no if's, and's, or but's. But getting caught...well, different story.

 

[Mike02z]

Totally understand what you are saying.

I will most likely order the Kooks and green cats and I will try and get a dyno before and after and confirm air fuel ratio at the time of the dyno and if it is safe and makes power I will not tune it but I certainly plan on verifying the air fuel ratio at WOT. I will not tune it if its safe plus I think this will be good info for everyone to know to see exactly how much the air fuel ration actually changes with headers and green cats along with seeing what the true gains or losses will be.

Gotcha. It will be interesting to see the before and after. If I was a betting man, I'd guess 15-20 additional RWHP without a tune. Keep us posted.:cheers:

 

[50 Deep]

Running long tube headers without a tune will be detrimental to your motor.

 

[firestarter2]

People actually care of their cars are legal lol. Times have changed.

I'd be VERY surprised if headers would make your car go so lean the ECU couldn't compensate between the fuel trims and knock sensors

 

[nastang87xx]

People actually care of their cars are legal lol. Times have changed.

I'd be VERY surprised if headers would make your car go so lean the ECU couldn't compensate between the fuel trims and knock sensors

This day and age, no. I ran headers with no tune on my '11 GT for a while and never had any issues with mixture. It was well within safe parameters. Yes a touch lean but by no means making the knock sensors looks their shit. But that's the beauty of wideband. A lot of Corvette guys would run headers too without a tune with no issues when they would switch to wideband.

 

[KGTG350]

I am curious if anyone has done just long tube headers and green cats WITHOUT a TUNE or intake?

I realize that a tune will maximize everything but just curious about the results, I can only find threads with intakes, tunes and E85.

Also curious why people who have tunes can install headers and not need retune but most say headers on a stock Ecu require a tune. If the air mass sensor meaures x amount of airflow I think the fuel system can richen up or lean out enough to compendate unless the wide open table is fixed and wont compensate.

I also know 0/2 sensor locations are now different and may give slightly inacurate readings.

Not looking to debate tunes just really curious if anyone has actually done this besides Kooks or American racing.

I ran my car for a week with kooks LT headers, high flow cats, no tune and 91 fuel. Also had the car dyno 420 to wheels (didn't get starting dyno so that number is irrelevant) low reading dyno

Sounded and drove fine. After tune and fuel of course I felt big changes.

I don't believe you need tune with headers. At least that's what I was told.

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