LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

MID LENGTH Headers/LT's Tune?!?!?

Old 02-18-2014, 08:37 PM
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MID LENGTH Headers/LT's Tune?!?!?

Hi i have a 95 z28 , Im in the market for headers. I know alot of people tell me get LTs but honestly they are pretty expensive and im a little Erie because roads in PA sucks and i dont want them to be hittings and the cars lowered the way it is. So ive seen these MAC mid length headers with a Y-pipe that goes into the cat. Claim 28.1 RWHP i dunno how true that is but they also keep the EGR/AIR hook ups and you can use your cat still. I have a mild comp cam,hyper-tech programmer,160 thermo,TPIS air filter and cold air intake ,TPIS air foil,and a corsa cat-back. I really wanna get a good tune done to the computer along with the headers but i am really stuck here on what ones to purchase!!!! LT's i was considering where TPIS LTs with Y-pipe no cat or EGR/AIR but it just seems deleting the emmisions is going to be more trouble and i dont even no if there are that great of HP/TQ gains from it. Is it better to leave the EGR&CAT or not I just want optimal HP/TQ gains, easy plug access,good price,and just easy install. any suggestions would be great. Im using this car just as a weekend driver and some auto cross.if that helps any. Plus i am looking for it to be louder and something to complement the CORSA.
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Old 02-19-2014, 06:00 AM
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Re: MID LENGTH Headers/LT's Tune?!?!?

There's no performance gain related to deleting EGR or AIR, other than a very small weight reduction. The AIR system only operates at startup to help the cat heat up faster, so if you don't have a cat you don't need AIR. But deleting it won't affect performance. You can delete the AIR system, and as long as the AIR circuit fuse and relay are healthy, you will not get a code in OBD-1.

EGR is not used at idle, above 3,500 RPM or at WOT, so it doesn't affect performance. You could even say it has the benefit of reducing the chance of detonation (spark knock) when lugging the engine at low RPM in the wrong gear. There are two codes for EGR. The one for the EGR vacuum solenoid circuit can be eliminated with a resistor in the end of the harness. Only the code for EGR flow would need to be tuned out, and the OBD-1 diagnostic is not very sensitive, often not producing a code.

The cat might cost you less than 5HP. What you do would depend on the emissions requirements where you live. There are no after-cat O2 sensors on your 95, so it will not set a code if cat is removed.
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Old 02-19-2014, 07:16 AM
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Re: MID LENGTH Headers/LT's Tune?!?!?

I've use the MAC mid length headers and y before. They were a great fit and clearance was like stock. I had them on a hot cam car, the following years I switched to LT's and could not feel a SOTP difference.
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Old 02-19-2014, 10:01 AM
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Re: MID LENGTH Headers/LT's Tune?!?!?

I have the Mac mid-lengths, plus a PCMforless tune and a 160 stat on my 93 LT1 Firehawk. I dynoed 309 rwhp and 342 rwtq. I picked up some very nice hp gains from the Macs. They give factory stock ground clearance and very good spark plug access. I really like mine. I also had the EGR and AIR deleted when I had the tune done.

Heres is a video of the Mac mid lengths on my Firehawk.


Last edited by Matts97camaro; 02-19-2014 at 10:04 AM.
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Old 02-19-2014, 10:09 AM
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Re: MID LENGTH Headers/LT's Tune?!?!?

Here is my LT1 Firehawk dyno with the Mac mid lengths, 160 stat, 3" ORP and tune,

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Old 02-19-2014, 04:26 PM
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Re: MID LENGTH Headers/LT's Tune?!?!?

Do you still have your cat and egr system hooked up? Or did you just delete the program in the computer. Because I was just thinking of getting the macs that allow the cat and egr system to still be used an then just sending out my computer to get it tuned. And your firebird is in excellent condition and those are some nice numbers there I wish I had a dyno in my city that would do my car it's all people with imports here. But I'm just curious if I'm better off. Just keeping the egr and cat. And do you have a link or number for pcmfprless if possible. And where do you recommend getting the MACS from
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Old 02-19-2014, 06:24 PM
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Re: MID LENGTH Headers/LT's Tune?!?!?

Thanks man. No i do not have the catalytic converter its been replaced with a 3" ORP (off road pipe). I do not have emissions in my county The EGR and AIR was deleted by PCMforless when they did my mail order tune.

I bought my headers used off ebay.

Here are some I found from TREperformance MAC 94-95 Camaro/Firebird LT1 Mid Length Chrome Headers with Y-Pipe

MAC 94-95 Camaro/Firebird LT1 Mid Length Ceramac Headers with Y-Pipe TF9495

Here is the link for PCMforless. PCMforless
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Old 02-19-2014, 07:21 PM
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Re: MID LENGTH Headers/LT's Tune?!?!?

So if i decide to run no cat would i just use a 3inch pipe or would i have to get a special pipe to fit the MAC y-pipe because in the picture it looks like it has a flange on the end of it or is that just a generic picture. Sorry for being a pain i just want to make sure i have exactly everything i need when i do this so im not waiting on certain parts just want to be 100% sure about all this. Also who makes your OTV wire kit because all most likely run that same set-up because it just looks so damn good and it will save the wires. Also thank you for the links. Def going to call PCMforless thats a great price. And what i meant when i asked about you deleting the EGR n AIR is the EGR system still hooked up to you headers and just deleted on the computer or do you just not have one at all anymore and if you dont what did you use to block off the ports on the headers? thanks

Last edited by Z28amustangklr; 02-19-2014 at 07:44 PM.
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Old 02-19-2014, 11:47 PM
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Re: MID LENGTH Headers/LT's Tune?!?!?

Here is the ORP 3" pipe you would need to get. It all bolts together very well. I took off my EGR and Air pump.

93-95 Camaro/Firebird LT1 Single Cat Car 3" Off Road Pipe To Stock

I got my OTV plug wires from Thunder Racing which is now out of business but i am sure someone else sells them.

I believe I used a 22 MM threaded plug for the ports on the headers. Advanced Auto parts or Autozone carries them or a local hardware store.

You will also need these if you remove your EGR like I did.

1993 - 1997 LT1 EGR Block-Off Plates - (3) Per Kit [2100] - $22.99 : UMI Performance, Inc.

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Old 02-20-2014, 01:23 AM
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Re: MID LENGTH Headers/LT's Tune?!?!?

alright cool is there any reason why you got rid of you egr kit or did you just want to get rid of it for looks?
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Old 02-24-2014, 04:09 PM
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Re: MID LENGTH Headers/LT's Tune?!?!?

Originally Posted by Z28amustangklr View Post
alright cool is there any reason why you got rid of you egr kit or did you just want to get rid of it for looks?
One of my EGR threaded fittings would not thread into my header on the passenger side. It was cross threaded. So I ended up just plugging the emission ports on the headers with a 22mm threaded plugs. Then also removed the AIR. Really cleaned up the engine bay after removing the AIR pump.
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Old 02-27-2014, 07:44 AM
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Re: MID LENGTH Headers/LT's Tune?!?!?

Originally Posted by Matts97camaro View Post
Here is my LT1 Firehawk dyno with the Mac mid lengths, 160 stat, 3" ORP and tune,

Pontiac Formula Firehawk Dyno - YouTube


Those are really impressive dyno numbers for you car with mods you have. What is the stock rating on your car, is it 285 HP.
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Old 02-27-2014, 08:18 AM
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Re: MID LENGTH Headers/LT's Tune?!?!?

My 1993 LT1 SLP Firehawk is rated at 300 hp from the factory. That is at the flywheel.

I must add when I dynoed the firehawk the owner of the shop guessed she would put out 285 rwhp max. He said based on all the other LT1 s he has dynoed with similar mods that is about what they produce. We did three pulls. They all were within 1 hp of each other. He was pretty shocked. He said it was pulling a few more hp than stock LS1 WS6 cars.

Thinking about going with a LT4 Hotcam or CC 503 with better valve springs and 1.6 roller rockers.
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Old 03-07-2014, 10:27 AM
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Re: MID LENGTH Headers/LT's Tune?!?!?

I have a '95Z and I went with the MAC mid-lengths and ORP as well. I am very happy with the fit and performance. I also went fo0r the Jethot coating. They have held up very well. I removed my air pump and EGR. I like that I am able to have the O2 sensors on the MAC pipes. I have a PCMFORLESS tune. Last dynorun I made was 300HP. You can see my mods in my sig. Not a lot overall. I also have stock exhaust from the ORP back. It has a good sound. Good volume when you get on it but very little when cruising which is what I like.

I also went with over the valve cover Taylor wires from Thunder Racing. I am now trying to replace them as I have a miss on the engine and have heard the Taylor's are known for this. I'm having trouble finding OVC wires.

Last edited by KYWes; 03-07-2014 at 10:35 AM. Reason: Added information
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Old 03-07-2014, 06:41 PM
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Re: MID LENGTH Headers/LT's Tune?!?!?

KYwes 300 rwhp are nice numbers ! Goes to show that the MAC mid length headers make power.

I havent had any problems out of my taylor wires. Had them on a previous LT1 and they were good also. I got mine from Thunder Racings but they have gone out of business.

You should be able to find a universal set where you would cut to length. Thats one thing I did not like about the Thunder Racing spark plug wire OTVC kit. I had to measure and cut to length. For the money I spent for those that should have already been done.
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