1-3/4 vs 1-7/8 American Racing LT Headers ( catted)

[Semp1]

I’ve read that you should build for the future with headers. I guess If boost the car this will be important to me later on. I’ve also read that with the bigger diameter you lose low end torque. From the numbers I’ve seen these 2 seem the exact same on the dyno at the top end Matter of fact the 1-7/8 produced slightly overall better numbers NA in the hp dept which it’s supposed to and the exact same tq numbers at the top end. My question is how much tq am I losing if I stay NA and do 1-7/8 in the low end? Don’t want to buy the 1-3/4 and say I should’ve just bought the 1-7/8 down the line. Also don’t want to buy 1-7/8 and say I should’ve went with the smaller diameter because it’s better for my application. My upgrades are a custom dyno tune , Roush cold air, Corsa Xtreme catback w/active. Keep in mind I might stay NA. The answer I seem to get is if I am staying NA. 100% just do 1-3/4. It’s better overall through the powerband. But if I am going to boost the car obviously 1-7/8. My question has a second part. If I do 1-3/4 and get the itch down the line will that hinder the supercharger at all?

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[cib24]

Aren't most of the gains made from deleting the cats and then upgrading the mid pipe and axle-back exhaust? You have guys N/A and one boost making great power with factory headers. As such, I don't think you should lose sleep over whetehr you choose 1 3/4 or 1 7/8. I'd go with the 1 3/4 if you are staying N/A and even if you are going for up to 950hp.

 

[Semp1]

Aren't most of the gains made from deleting the cats and then upgrading the mid pipe and axle-back exhaust? You have guys N/A and one boost making great power with factory headers. As such, I don't think you should lose sleep over whetehr you choose 1 3/4 or 1 7/8. I'd go with the 1 3/4 if you are staying N/A and even if you are going for up to 950hp.

From everything I read and every one I’ve spoken too high flow cats vs catless create a difference of less than2- 5hp but guarantee passing emissions. I’ll sacrifice the 2-5hp to not have an issue with an inspection. Obviously stock cats vs catless is a different story.

 

[3star2nr]

I’ve read that you should build for the future with headers. I guess If boost the car this will be important to me later on. I’ve also read that with the bigger diameter you lose low end torque. From the numbers I’ve seen these 2 seem the exact same on the dyno at the top end Matter of fact the 1-7/8 produced slightly overall better numbers NA in the hp dept which it’s supposed to and the exact same tq numbers at the top end. My question is how much tq am I losing if I stay NA and do 1-7/8 in the low end? Don’t want to buy the 1-3/4 and say I should’ve just bought the 1-7/8 down the line. Also don’t want to buy 1-7/8 and say I should’ve went with the smaller diameter because it’s better for my application. My upgrades are a custom dyno tune , Roush cold air, Corsa Xtreme catback w/active. Keep in mind I might stay NA. The answer I seem to get is if I am staying NA. 100% just do 1-3/4. It’s better overall through the powerband. But if I am going to boost the car obviously 1-7/8.

On most engines 1-3/4 is the best choice up till 440ci on coyote engines thats NOT the case since we have variable valve timing and IMRCs on the intake manifold.

Why does this matter? The ecu uses the variable runners and varrying cam timing to make up the losses in low end torque. This is something LS motors dont have...

With our engines the 1-7/8 make more power and have virtually no loss in low end torque N/A

So get whatever u can get a good deal on. THE only advantage to 1-3/4 is the thinner walls give some clearance during install and possibly will prevent u from getting false knock when the engine torques and the headers touch something... Again though this isnt really an advantage as it depends on brand...

So just go with a company you know has a good record for quality and fitment. The bigger companies use CNC mandrel benders and welding jigs so the pipes are dead on accurate every kit.

Thats what you pay for...

 

[cib24]

From everything I read and every one I’ve spoken too high flow cats vs catless create a difference of less than2- 5hp but guarantee passing emissions. I’ll sacrifice the 2-5hp to not have an issue with an inspection. Obviously stock cats vs catless is a different story.

Well, I guess it depends on where you live but 1-2 owners have tried high flow cats here in the UK and failed spectacularly on emissions, and that is on the non-GPF equipped pre-2019 models. So, if you go for high flow cats or catless in most places in the world then you will need a friendly emissions shop.

 

[3star2nr]

I'd also advice you to stay catted. While catless does make more powerbit also makes the car smell horrible. And breathing in NOX will fuck u up in the long run. COPD is no joke

 

[Semp1]

Well, I guess it depends on where you live but 1-2 owners have tried high flow cats here in the UK and failed spectacularly on emissions, and that is on the non-GPF equipped pre-2019 models. So, if you go for high flow cats or catless in most places in the world then you will need a friendly emissions shop.

Custom tunes should prevent failures if tuned properly. And I’m not talking about email tunes.

 

[15GTCA]

I know that here in CA you can not change out the cats at all or you will fail emissions although some have been able to get away with it.

 

[cib24]

I'd also advice you to stay catted. While catless does make more powerbit also makes the car smell horrible. And breathing in NOX will fuck u up in the long run. COPD is no joke

Very true. I had a catless rotary once and you can imagine how bad that was. Pretty sure I'll end up with cancer later on as a result.

Why people go catless to make 5-10 more hp that you can't even feel when boosted at 800hp already I will never understand. Most users on here don't even subject their cars to that much stress. A 1/4 mile drag run is peanuts compared to running a boosted car on a circuit for 20-30 minutes at a time, which most people with forced induction do not do.

 

[3star2nr]

Very true. I had a catless rotary once and you can imagine how bad that was. Pretty sure I'll end up with cancer later on as a result.

Why people go catless to make 5-10 more hp that you can't even feel when boosted at 800hp already I will never understand. Most users on here don't even subject their cars to that much stress. A 1/4 mile drag run is peanuts compared to running a boosted car on a circuit for 20-30 minutes at a time, which most people with forced induction do not do.

So the reason race cars go catless is because for competition with millions in sponsor money on the line thwy need every edge. Those engines are also only designed to survive a season.

Also with some fuels like e85 they tend to contaminate the cats and foul o2 sensors so they just get rid of them all together. Plus the car spits flames...

All that said I would always run catted on a street car

 

[cib24]

So the reason race cars go catless is because for competition with millions in sponsor money on the line thwy need every edge. Those engines are also only designed to survive a season.

Also with some fuels like e85 they tend to contaminate the cats and foul o2 sensors so they just get rid of them all together. Plus the car spits flames...

All that said I would always run catted on a street car

I don't disagree with you from a competition perspective but I wasn't referring to those cars. I was referring to the majority of people that de-cat their cars, which is like 50-75% of the mod community, not just the Mustang one. There is no reason to run catless on a street car on the road. If you want to build a quick removal solution for track use that's cool and then you can run your E85 on the circuit without worrying about harming the cats. Other than that though it's just stupid and all a person is doing is poisoning themselves and everyone around them in the process for 5-10 hp that you can't feel in a 4,000lb car.

 

[Semp1]

So I’m sorry but back on topic. Would the consensus be to go with the 1-7/8? Ha

 

[3star2nr]

I don't disagree with you from a competition perspective but I wasn't referring to those cars. I was referring to the majority of people that de-cat their cars, which is like 50-75% of the mod community, not just the Mustang one. There is no reason to run catless on a street car on the road. If you want to build a quick removal solution for track use that's cool and then you can run your E85 on the circuit without worrying about harming the cats. Other than that though it's just stupid and all a person is doing is poisoning themselves and everyone around them in the process for 5-10 hp that you can't feel in a 4,000lb car.

I agree kinda like the people DDing on e85 haha

 

[3star2nr]

So I’m sorry but back on topic. Would the consensus be to go with the 1-7/8? Ha

Thats what id do.

 

[Bladerunner70]

...makes the car smell horrible. And breathing in NOX will fuck u up in the long run. COPD is no joke

...I had a catless rotary once and you can imagine how bad that was. Pretty sure I'll end up with cancer later on as a result.

...There is no reason to run catless on a street car on the road. ...it's just stupid and all a person is doing is poisoning themselves and everyone around them in the process.

Wow. Just..., Wow!

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