Longtube headers/

**98maro** · 07-08-2010, 01:38 PM

Hey guys and girls. I'm bk again with more questions
My car has the cats broken
They are makin noyse inside 1 of them
So I'm just gonna take em off
And I was thinking bout gettin some LT headers
My questio is. If I get em do I have to tune the car?
Or I can run the car wit LT headers no cats
I knw it will have the gas smell all the time
So at da same time I was thinking bout gettin high flow cats
Any advice,?
Thanks

**dennis ss** · 07-08-2010, 01:41 PM

You would need to tune your car to get the maximum gains from the headers. Also if you remove the cats you will have to tune the rear O2 sensors out.

**pajeff02** · 07-08-2010, 01:41 PM

Anything that changes the airflow through your engine should then be compensated for via tuning. Headers definitely have an impact on airflow. Strongly recommend a mail order tune from Frost to get the most out of your mods.

**98maro** · 07-08-2010, 01:56 PM

Thanks for the replies
What could happen if I dnt get the tune for now ?

Cuz I have more plans for it but not right now
That's why I dnt want to do the tune right now
I want to get
Ls6 intake
Ls6 ported and polish heads
Polish and throttle body
Lifters
Roller rockers
Pushrods
LT headers
Small cam
High flow cats
And all the free mods with
Slp air lid

Once I get all thR

**98maro** · 07-08-2010, 01:57 PM

Once I get all that want to get the tune
But I wanted to start with the headers

**dennis ss** · 07-08-2010, 01:59 PM

Depending on how long it takes you to get all the mods listed you can go without a tune for a little while but the car will run like crap. I don't know your money flow but if it takes more than a month or so to get all those mods then I would make sure you get the tune, IMO

**98maro** · 07-08-2010, 02:08 PM

It's gonna take a while
To do all that probably will have everithin by next year
I dnt wanna have the car runnin like dat for a long time
So I should buy the parts and install en all together and get it tuned

**Vexzer** · 07-08-2010, 02:26 PM

Originally Posted by 98maro

What could happen if I dnt get the tune for now?

By just changing to LT's you prolly won't be able to tell any difference in driveability, but you might not pass CA emissions if you lose the cats. If you lose the cats, you will need a "tune" for the sake of killing the secondary o2's. Otherwise you'll be stuck with a 'check engine' light.

**Too Fast** · 07-08-2010, 02:40 PM

Originally Posted by dennis ss

Depending on how long it takes you to get all the mods listed you can go without a tune for a little while but the car will run like crap. I don't know your money flow but if it takes more than a month or so to get all those mods then I would make sure you get the tune, IMO

Wrongo. I didn't get my tune (from Frost) for 3.5 years after I put on my stuff, and I'm not sure I really needed it. I put on my Hooker ceramic LTs and ORY, lost my EGR, rear O2s and AIR pump, had no issues except the SES light was on. Unless you say that 1.5 MPG highway improvement and a higher trap speed at the 1/4 mile dragstrip is a problem. It does feel a bit more urgent when I get on it when the engine is over 3500 RPM or so since the tune, but my most recent trap speeds (107.x) don't back up the tune advice. 9 months after I put on the headers/ORY, on a very nice (mid 50 degree temps) October evening, I ran 7 times with trap speeds of 109.x, a best that night of 12.89 109.85. All that with 1.99-2.1 60 ft times.

These MAF cars are self tuning to an extent, if the PCM senses higher airflow (which it will with the addition of LTs, since the engine's efficiency is better) it will alter the fuel map. But to always get the most gains, a mail order tune from someone like Frost is a given, for a stock car or a bolt-on car. For the best tune, you need to get to the dyno with someone who knows what they are doing, and monitor A/F ratios so as not to be too lean.

**pajeff02** · 07-08-2010, 02:45 PM

Originally Posted by Too Fast

Wrongo. I didn't get my tune (from Frost) for 3.5 years after I put on my stuff, and I'm not sure I really needed it. I put on my Hooker ceramic LTs and ORY, lost my EGR, rear O2s and AIR pump, had no issues except the SES light was on. Unless you say that 1.5 MPG highway improvement and a higher trap speed at the 1/4 mile dragstrip is a problem. It does feel a bit more urgent when I get on it when the engine is over 3500 RPM or so since the tune, but my most recent trap speeds (107.x) don't back up the tune advice. 9 months after I put on the headers/ORY, on a very nice (mid 50 degree temps) October evening, I ran 7 times with trap speeds of 109.x, a best that night of 12.89 109.85. All that with 1.99-2.1 60 ft times.

These MAF cars are self tuning to an extent, if the PCM senses higher airflow (which it will with the addition of LTs, since the engine's efficiency is better) it will alter the fuel map. But to always get the most gains, a mail order tune from someone like Frost is a given, for a stock car or a bolt-on car. For the best tune, you need to get to the dyno with someone who knows what they are doing, and monitor A/F ratios so as not to be too lean.

By chance, did you log and compare your pre and post tune A/F ratios or STFT's/LTFT's? I agree that the PCM will compensate based upon feedback from the O2 sensors. Just curious as to what the difference was.

**dennis ss** · 07-08-2010, 02:53 PM

When I had my cats deleted and my ORY and exhaust installed my car ran like shit. It sucked twice as much gas and just generally ran crappy. Car ran super rich as well. After the tune on a laptop my car runs like a bat out of hell and no more black smoke. To each his own, I'm speaking from my personal experience. My SS is different car after a tune

**98maro** · 07-08-2010, 02:54 PM

Ok if I got it right
If I remove the cats had to be tuned?
If I run LT with cats could run fine for a while ?
Could I use high flows instead of stock cats?

**Too Fast** · 07-08-2010, 02:54 PM

^^^nope. I have looked at the trims now, they are +/- 3% of desired, so that's right where he wants it. I attribute my excellent MPH that night in October more to the perfect DA then, more then I think I lost something with the tune. If I could go back to that night with the current tune, I'm pretty sure it would've hit over 110.

I should've looked at the fuel trims before I sent the PCM away, but didn't. PCM compensates based not only on O2 sensors, but other variables like MAF, ECT, as I'm sure you know. It would be nice to have a wide band O2.

(was responding to pajeff02)

**98maro** · 07-08-2010, 02:56 PM

Wat I want to do on mine
LT headers y pipe. Cut out.
And 1 high flow cat

**Too Fast** · 07-08-2010, 02:57 PM

I don't think you can do that in the land of Cali, can you? Must have the cats in the OE location. I like the cut out tho.

**98maro** · 07-08-2010, 03:04 PM

Here in Cali. LT and high flows are illegal
I want to get the headers cuz it sounds sick
And remove or change the cats because it will feel better more horses

Thanks
I like the cutouts
I'm keeping the muffler

**35th-ANV-SS** · 07-08-2010, 03:33 PM

You cannot pass smog in Cali with LTs...period. Not legally at least. And I agree with too fast, a tune is not a necessity with LTs, but it is recommended.

There are plenty of people running LTs without a tune, and for a long time. Will you get the most out of them without a tune? Of course not, but again I don't think it is a live or die situation.

**98maro** · 07-08-2010, 04:16 PM

I knw it won't pass the smog with LT
I'm ok with that. I'm gonna do the smog check next week then I have 2 years ahead of me for the emissions again
I just want to make sure what could happen if I dnt get it tuned
I will tune it when I'm done with the mods

**00ls-1** · 07-09-2010, 09:09 PM

i know the computer comoensates i put an 85mm maf sensor and the car wanted to die when i did it but i took it out on the street and ran it for a second and then just floored it and when i stopped it ran fine....btw i noticed a difference in powere w the bigger maf sensor

**pajeff02** · 07-10-2010, 03:53 AM

Originally Posted by 00ls-1

i know the computer comoensates i put an 85mm maf sensor and the car wanted to die when i did it but i took it out on the street and ran it for a second and then just floored it and when i stopped it ran fine....btw i noticed a difference in powere w the bigger maf sensor

In all seriousness... ditch the 85mm MAF unless you have it tuned. These simply lean out your engine and are not recommended. The stock MAF is good up to around 500 hp. Also, it should not be modifed -- leave the screen and blade in place and do not port it.