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Discussion Starter · #1 ·
Is it true that you can lose a little of your low end power when you go with an exhaust with to low of back pressure?
Has anyone noticed this with the banks exhaust?

thanks
 

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Not at all...

I have felt nothing being lost. I have had it on for almost a month now and it has only pleased me everyday. Love the loud growl but it is not as loud as others say it is. Only when hitting the gas and at idle not any other time. Nothing feels lost at all.
 

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KansasFrontier,

It is very true that you can lose a ton of low end torque with too big of an exhaust system. Anything bigger than 2.5" is way to big for the 4.0L Frontier and will lose low end torque and throttle response.

What pipe size should I use for a street application?
In general, the following guidelines should be applied for street applications.

2" tubing up to 100 hp per pipe

2.25" tubing up to 160 hp per pipe

2.5" tubing up to 200 hp per pipe

3" tubing up to 300 hp per pipe

Thanks,
David
 

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David,

I have a question about the pipe size to HP chart you posted. Being as our trucks (the 05/06 4.0L anyway) make 265HP, that would be 122.5HP per pipe using your guideline (if it were true dual exhaust all the way). So, if I'm reading this right, and I wanted a 2 into 1 system with a single muffler and single tail pipe, I would need the head pipes to be 2.25" running to a "Y" with a 3" output, a 3" in and out muffler and a 3" tail pipe? That's almost what I had with the Banks system with the exception of the Banks has 3" head pipes and a 3" in and out "Y"! This doesn't seem right.

What would the optimal system be for our trucks? I was thinking 2.5" the whole way, but now I'm wondering it it sould be 2.25" to the "Y" and then 2.5" out, through the muffler and the tail pipe! What amI I missing/
 

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Hello Paul,

We have not found the perfect combination as of yet. However the biggest the system should ever be is 2.5". Even if you went with a 2.25" it would still be ok.

I will see if I can find a better chart with pipe diameter vs. cubic inches.

Thanks,
David
 

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Thanks David! I think I'll wait till you guys complete all your R&D and see what you come up with! I'll put my order in now:

Optimized exhaust that will increase HP, retain torque and gas mileage, preferable tuned to take full advantage of the AirAid intake products while maintaining a mellow exhaust note with no interior drone, all for under $400.00!

I know, I don't ask for much! :lol:
 

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Discussion Starter · #7 ·
thanks

Thanks for all of your imput
I think that will help me make a decision.
It is very difficult to decide which exhaust to use when you don't have any
numbers infront of you to compare.
 

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David,

This is a very interesting topic. I went with the stock pipe to the back cats on my
truck and then they ran a 2 1/4" pipe into a pair of 12" resonators. From there it
went into a 22" dual in dual out Flo-Pro muffler. They used a pair of 2 1/4 tailpipes
back to a 3 1/4 od double wall ss tip.

Does the size of the tailpipe effect the gasoline mileage as it does the torque? I lost
a couple of mpg with my exhaust system. Not sure if it is the true duals that caused
that or something else.

You might look at the installation write up the Mike3_21_21 did for us on the Volant CAI's we just bought. Volant just encloses a spec sheet showing what is included,
but no instructions on how to install it on our trucks.

You might talk with Volant about including his instructions with their Frontier kits. I
think he is going to rewrite the instructions to make them a little easier to follow. i
would think Volant would be glad to get this sort of information and maybe get some
sort of refund on his kit for the work he went to to get this information to those of us
who are not sure enough of ourselves to just start pulling things off of our trucks.

His instructions have made me feel comfortable with the Volant installation. I was cer-
tainly having a time trying to figure out how to get some of the plastic pieces off of my
truck until he showed me how to do it.

OkieScot
 

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Thanks OkieScot,

I haven't posted it yet but I'll work on the install instructions.

And as for my first tank of gas, first quarter without Volant, up almost 1 mpg. I have been playing a bit though. I'm trying to baby it now but boy you step on the gas and watch that needle drop. But that's only when needed.
 

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Discussion Starter · #10 ·
I am starting to get the feeling that an aftermarket exhaust will most likely lower your gas mileage without much or any horsepower gains.

I am a little skeptical because my last vehicle (a 1995 bronco) actually felt more slugish when the less restrictive exhaust was put on. Granted a local muffler shop fabricated the entire kit.

I just have a hard time believing that $400-600 worth of exhaust is really going to be worht it.

Maybe the CAI systems everyone is raving about would be a better way to go.
 

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now im scared

I definitly like my low end power, maybe you guys can help me with my worries...will headers also lose low end performance? will headers and exhaust actually work together to improve it? thanks
 

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From what I've been told, it's because companies are using 3" pipes on a V6 that the low end torque is being lost, however, high end gain will be there. I think a mandrel bent 2.5" system of a 2.25" into 2.5" single would give HP gains without loss of low end torque. I'm still debating on which way to go. From what I've see of the stock system, the stock "Y" pipe seems to be very restrictive. Magnaflow makes a 2.25" in 2.5" out "Y" that Autoanything sells for $25.00. I'm wondering if just replacing the stock "Y" with this piece would give any noticable improvements? Here's a Pic:

 

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Discussion Starter · #13 ·
exhaust

From what I've been told, it's because companies are using 3" pipes on a V6 that the low end torque is being lost, however, high end gain will be there. I think a mandrel bent 2.5" system of a 2.25" into 2.5" single would give HP gains without loss of low end torque. I'm still debating on which way to go. From what I've see of the stock system, the stock "Y" pipe seems to be very restrictive. Magnaflow makes a 2.25" in 2.5" out "Y" that Autoanything sells for $25.00. I'm wondering if just replacing the stock "Y" with this piece would give any noticable improvements? Here's a Pic:

I think you might get a slight gain, but honestly I don't really think you will feel any improvement.
but I have been wrong before.
I do think you are on to something. The diameter of the pipe, and the amount of back pressure is very important to whether you get gains or losses in your power band and also where in your power band you get them.
 

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Don't know if I'm really all that concerned about a tremendous gain as I don't race my truck! I'm looking for a free flow outlet for the engine that might help increase gas mileage. I have seen a drop in gas milage since I removed the Banks system, but have also noticed an increase in low end grunt! I guess it's a trade off!

I went out and measured the pipes on the stock system, and it appears the pipes coming off the CATs are 2" and the pipe after the "Y" to the muffler and then out the back are 2.25"!

So, I would think a custom 2.25" to a Magnaflow "Y" and then a 2.5" from the "Y" through an 18" long Magnaflow muffler and out the tail pipe should open things up a good bit and still maintain a mellow exhaust note! Why can't an aftermarket company come up with a set-up like that? :roll:
 

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Discussion Starter · #15 ·
exhaust

That makes sense
 

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I found this on the Magnaflow website:

PIPE DIAMETER AND PERFORMANCE
Keep in mind that the goal is to improve exhaust flow. In most cases, just changing the restrictive OEM muffler and replacing it with the same size straight-through, Wide Open Performance MagnaFlow muffler will do this job.
To reduce additional backpressure, the OEM exhaust tubing can be replaced with madrel-bent tubing of the same size or one size up from the OEM. As a general rule, you can enlarge the pipe diameter of your OEM exhaust system by 1/4- to 1/2-inch to increase your horsepower. However, any additional increase in pipe diameter is likely to decrease your performance; specifically, low end torque.

Bigger is not always better.
 

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I have no idea about headers, I've never had a pair on a vehicle before. I just know I lost a lot of low end when I had the Banks Exhaust on my truck, and being as I don't race it, or spend much time at WOT, I prefer something that will keep the low end while freeing up the exhaust flow in the interest of better gas mileage. I would think the same principle would apply with the entire exhaust system.
 

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I just installed my banks exhaust. Well start up sounded really good, its loud but not too loud. I drove around the city a little and it has a drone at about 2k-2500 rpm, that I could see it being too loud but it doesnt bother me too much, my older truck was alot louder. Other than that Im a happy person. Once I drive on the highway, I will post about the sound. Thanks Paul!
 

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I'm glad you like it! I don't think you'll notice much difference on the highway, it quiets down once you hit cruising speed. It was really just the drone I didn't like!
 
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