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Discussion Starter #1
I don't see why I couldn't. I used to have a 1995 Z/28 Camaro that made less power and ran a 3" aftermarket exhaust just fine. I would imagine this engine would breathe better from a 3" exhaust, and I don't like the idea of spending $1k+ to replace the piping with the same 2.5" diameter piping (I have a 6-speed).

Also, for the record, not talking about friendoffur's insanely long SRT header swap here. That looked like a nightmare!

Is there any reason why the 3" headers/exhausts won't fit? I would be doing the whole thing at the same time -- headers, mid-pipe, cat-back. Thanks!
 

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Thanks for posting that. It looks like nobody in that thread has really tried it though, or has any real fitment issues posted. As far as the 3" pipes being too big for the power, I don't believe it. But what I'm wondering is whether there would be any fitment issues?
 

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Thanks for posting that. It looks like nobody in that thread has really tried it though, or has any real fitment issues posted. As far as the 3" pipes being too big for the power, I don't believe it. But what I'm wondering is whether there would be any fitment issues?
I am pretty sure 3" primary tube headers are not going to have enough room to make all the bends and clear all the obstacles in the engine compartment. A 3" system from the collectors back may work though.
 

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I have seen a chart that shows HP rating and exhaust diameter suggestions. If you go too big you will loose low end torque because of the loss of backpressure from my understanding. I could be wrong though.
 

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Welcome to the MoPar world You can go headers with 3" but not for under anywhere close to 1k try closer to 2.5k for a good setup you will also need a custom tune and tuner. For a decent set of headers you will be at or over 1k depending on the brand/ sale you get.
 

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As I read the thread, I find myself asking "why" - as in "Why do you want to do this?" So lets start with the end in mind. What are you trying to accomplish and what results are you expecting to get out of it? Are you planning any other changes over time? If so, what is the end game so we understand how this might fit (or not) with what you are trying to end up with. By knowing that we should be able to give you a more thoughtful answer.

Also - do you live in an emissions prgram state? That will affect the answer....
 

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Hopefully this article will help.


[FONT=Verdana, Arial, Helvetica, sans-serif]FAQ's: MagnaFlow's Frequently Asked Questions [/FONT]FAQ's
Question: Why ISN'T a bigger pipe always better?

Answer: Don't be fooled! Bigger is not better! Many people think that having the biggest diameter pipe is the best way to make power.
Not true. Due to a variety of factors, extensive testing is required. We've dyno'd extensively and our systems yield optimum power increases. Some manufacturers claim even higher horsepower numbers.

It is a fine line to reduce backpressure while maintaining good exhaust velocity. It is not about getting the biggest pipe, it is about getting a more efficient pipe diameter while maintaining exhaust velocity.

There has to be a balanced design to enhance the maximum engine output, exhaust gas velocity, and sound. For example, imagine blowing air through a straw (comparing it to a smaller diameter pipe). This would take time to release all the air from your mouth, and you would feel pressure in your mouth while doing so. Now imagine blowing air through a paper towel roll (comparing it to a larger diameter pipe). You will relieve all your air much faster and feel little or no air pressure in your mouth because of the larger capacity of the tube. This is why it is important to get the correct size piping in order to relieve backpressure while maintaining thermal efficiency.

[FONT=Verdana, Arial, Helvetica, sans-serif]Use the guide below when calculating pipe size for custom exhaust work. 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 the job.[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]To reduce additional backpressure, the OEM exhaust tubing can be replaced with mandrel-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.[/FONT]


[FONT=Helvetica,Arial]ENGINE SIZE---- [/FONT][FONT=Helvetica,Arial]HORSEPOWER ----[/FONT][FONT=Helvetica,Arial]MUFFLER INLET/OUTLET [/FONT]
------------------------------------------------------Single Exhaust---- Dual Exhaust
[FONT=Helvetica,Arial]150-200 CID -------[/FONT][FONT=Helvetica,Arial]100 to 150------------- [/FONT][FONT=Helvetica,Arial]2" to 2-1/4"------------[/FONT][FONT=Helvetica,Arial]2"[/FONT]
[FONT=Helvetica,Arial]200-250 CID -------[/FONT][FONT=Helvetica,Arial]100 to 200------------- [/FONT][FONT=Helvetica,Arial]2-1/4" to 2-1/2"----- [/FONT][FONT=Helvetica,Arial]2" to 2-1/4"[/FONT]
[FONT=Helvetica,Arial]250-300 CID -------[/FONT][FONT=Helvetica,Arial]150 to 250 -------------[/FONT][FONT=Helvetica,Arial]2-1/2" to 3" ----------[/FONT][FONT=Helvetica,Arial]2" to 2-1/2"[/FONT]
[FONT=Helvetica,Arial]300-350 CID --------[/FONT][FONT=Helvetica,Arial]200 to 350 ------------[/FONT][FONT=Helvetica,Arial]2-1/2" to 3"---------- [/FONT][FONT=Helvetica,Arial]2-1/4" to 2-1/2"[/FONT]
[FONT=Helvetica,Arial]350-400 CID --------[/FONT][FONT=Helvetica,Arial]250 to 550 ------------[/FONT][FONT=Helvetica,Arial]3" to 4"---------------- [/FONT][FONT=Helvetica,Arial]2-1/2" to 3"[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]Use as a general guide for engine size and performance[/FONT]
 

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Hopefully this article will help.


[FONT=Verdana, Arial, Helvetica, sans-serif]FAQ's: MagnaFlow's Frequently Asked Questions [/FONT]FAQ's
Question: Why ISN'T a bigger pipe always better?

Answer: Don't be fooled! Bigger is not better! Many people think that having the biggest diameter pipe is the best way to make power.
Not true. Due to a variety of factors, extensive testing is required. We've dyno'd extensively and our systems yield optimum power increases. Some manufacturers claim even higher horsepower numbers.

It is a fine line to reduce backpressure while maintaining good exhaust velocity. It is not about getting the biggest pipe, it is about getting a more efficient pipe diameter while maintaining exhaust velocity.

There has to be a balanced design to enhance the maximum engine output, exhaust gas velocity, and sound. For example, imagine blowing air through a straw (comparing it to a smaller diameter pipe). This would take time to release all the air from your mouth, and you would feel pressure in your mouth while doing so. Now imagine blowing air through a paper towel roll (comparing it to a larger diameter pipe). You will relieve all your air much faster and feel little or no air pressure in your mouth because of the larger capacity of the tube. This is why it is important to get the correct size piping in order to relieve backpressure while maintaining thermal efficiency.

[FONT=Verdana, Arial, Helvetica, sans-serif]Use the guide below when calculating pipe size for custom exhaust work. 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 the job.[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]To reduce additional backpressure, the OEM exhaust tubing can be replaced with mandrel-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.[/FONT]


[FONT=Helvetica,Arial]ENGINE SIZE---- [/FONT][FONT=Helvetica,Arial]HORSEPOWER ----[/FONT][FONT=Helvetica,Arial]MUFFLER INLET/OUTLET [/FONT]
------------------------------------------------------Single Exhaust---- Dual Exhaust
[FONT=Helvetica,Arial]150-200 CID -------[/FONT][FONT=Helvetica,Arial]100 to 150------------- [/FONT][FONT=Helvetica,Arial]2" to 2-1/4"------------[/FONT][FONT=Helvetica,Arial]2"[/FONT]
[FONT=Helvetica,Arial]200-250 CID -------[/FONT][FONT=Helvetica,Arial]100 to 200------------- [/FONT][FONT=Helvetica,Arial]2-1/4" to 2-1/2"----- [/FONT][FONT=Helvetica,Arial]2" to 2-1/4"[/FONT]
[FONT=Helvetica,Arial]250-300 CID -------[/FONT][FONT=Helvetica,Arial]150 to 250 -------------[/FONT][FONT=Helvetica,Arial]2-1/2" to 3" ----------[/FONT][FONT=Helvetica,Arial]2" to 2-1/2"[/FONT]
[FONT=Helvetica,Arial]300-350 CID --------[/FONT][FONT=Helvetica,Arial]200 to 350 ------------[/FONT][FONT=Helvetica,Arial]2-1/2" to 3"---------- [/FONT][FONT=Helvetica,Arial]2-1/4" to 2-1/2"[/FONT]
[FONT=Helvetica,Arial]350-400 CID --------[/FONT][FONT=Helvetica,Arial]250 to 550 ------------[/FONT][FONT=Helvetica,Arial]3" to 4"---------------- [/FONT][FONT=Helvetica,Arial]2-1/2" to 3"[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]Use as a general guide for engine size and performance[/FONT]
VERY good post there which I completly agree with!! Velocity is very often overlooked in the search for horepower when doing exhaust. There is one thing that I feel is being overlooked in this equation that you posted. The catalytic converters. Those pipe sizing guidlines are 100% correct for a car without them but maybe not so much with them. Imagine blowing through that same straw they used for an example but now useing the two fingers that hold the straw...crimping down on the straw a bit in the middle. It won't matter how big that straw is past the crimp....the crimp is the big restriction. That may well be true with your catalytic converters in the same way.
 

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I have seen this analysis before and agree that the R/T exhaust diameter is optimal in the 2-1/4" to 2-1/2" range. You may notice that exhaust manufacturers promote their 2-1/4" and 2-1/2" systems for the R/T and 3" systems for the SRT.
 

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I ran into a guy that went with 3" as a cat-back system. It sounded great and he swore it had more power. However, I agree with the chart, the RT needs the 2.5".
 

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The best exhaust flow has relates to power explaination I've ever read. Two of the most critical things has relates to our cars that I read was #1...The cats are THE big power loss problem no matter what you do downstream if your mufflers are of adaquate flow. #2...That cross-over from the factory...or a custom X pipe...is all but useless if not installed BEFORE the cats.:smileup::smileup::smileup:
 

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That cross-over from the factory...or a custom X pipe...is all but useless if not installed BEFORE the cats.:smileup::smileup::smileup:
I noted that the Zoomers / Speedlogix brand exhaust system once did, but no longer includes an X-pipe. However, I have also discovered that at least one vendor still has stocks of this system with the X-pipe if that is what you really want to have.
 

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I know this thread is a little old but if anyone is still curious, I'm running 3" MagnaFlow Comp series 16886 on my 13' R/T Plus and love the sound! Can't say I really noticed any loss in low end and I'm also about to switch to srt headers and mids!
 

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Discussion Starter #20
I'm running a full 3" system -- Kooks SRT headers and 3" mids into a Borla ATAK 3" cat back exhaust. It has gobs more power across the band, definitely a gain in low-end torque as well. Not sure how it would fare back-to-back against a 2.5" system, but you are definitely looking at a lot more power going to a full 3".
 
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