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Discussion Starter #1
On my list of things to do to my 2014 Mazda3 2.5l is to get an exhaust. Sadly I have the sedan variant and there seem to be fewer options out there for it. Anyone have any experience or good recommendations for an exhaust that #1 fits (duh), and #2 is on the louder end (I realize it will never be a loud car but indulge me for a moment)?
 

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2018 Mazda 3 GT called Coffee.
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Corksport and Racing Beat both make exhausts for the sedan. Both are louder than stock, but the Racing Beat exhaust is considered to be the least annoying (loud) exhaust.
CK
 

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Discussion Starter #3
Corksport and Racing Beat both make exhausts for the sedan. Both are louder than stock, but the Racing Beat exhaust is considered to be the least annoying (loud) exhaust.
CK
After finding a video of the 80mm catback from Corksport, I have to say it sounds pretty good. However, it does cost 1k and after reading some other posts on here I see people are saying there are downsides to an 80mm catback?
 

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Yes. You are removing your 2nd cat with that system.

I would go with Racing Beat axle-back, if I were you. It's a really well made product that will work well for a DD.
CK
 

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Yes. You are removing your 2nd cat with that system.

I would go with Racing Beat axle-back, if I were you. It's a really well made product that will work well for a DD.
CK
Exactly what is the issue/power loss by using an 80mm exhaust? Because after researching the racing beat, a video I managed to find made the car sound exactly the same, and it seems pointless to spent $500 on a system that will make your car sound the same with no benefits...
 

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It can. It usually also is in violation of law in most places. If you're on a track, have at it.

With a performance exhaust, bigger is not always better. Backpressure is also a bad thing despite what you read. Google something called exhaust valve scavenging. Fluid mechanics works like this: if you have a gas flowing at a certain velocity through a pipe of a certain diameter and then it goes to a larger pipe it will slow down. The gas velocity is important because there is a short time of valve overlap in the engine where both intake and exhaust valves are open at the same time. The exhaust gas leaving the cylinder creates a suction on the intake to help pull fresh air in. Increase pipe diameter, and you reduce this effect as gas velocity slows down.
This is where the misconception of 'needing backpressure' comes from.

In reality, backpressure is the resistive force of the gas flowing in the pipe. This slows down the exhaust! A pipe too small can do this. The trick is to reduce the backpressure as much as possible without making the pipe too large. That is to keep the exhaust velocity as high as possible with as little restriction as possible.

This is done by using mandrel bends instead of crush bends and increasing the pipe size to the sweet spot where there's less backpressure but velocity does not start to fall off.

Usually, manufacturers build the exhaust cheap. This means it's very restrictive. With these cars, Mazda did a good job. It already flows well so there's very little room for improvement.

With a restrictive muffler, they may add a larger pipe to compensate so simply removing the muffler may degrade performance. Depends on how it's built. If the pipe is sized right, you'd be removing considerable restriction caused by the exhaust.

Not quite as simple as you thought I'm guessing.
 

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Discussion Starter #8
It can. It usually also is in violation of law in most places. If you're on a track, have at it.

With a performance exhaust, bigger is not always better. Backpressure is also a bad thing despite what you read. Google something called exhaust valve scavenging. Fluid mechanics works like this: if you have a gas flowing at a certain velocity through a pipe of a certain diameter and then it goes to a larger pipe it will slow down. The gas velocity is important because there is a short time of valve overlap in the engine where both intake and exhaust valves are open at the same time. The exhaust gas leaving the cylinder creates a suction on the intake to help pull fresh air in. Increase pipe diameter, and you reduce this effect as gas velocity slows down.
This is where the misconception of 'needing backpressure' comes from.

In reality, backpressure is the resistive force of the gas flowing in the pipe. This slows down the exhaust! A pipe too small can do this. The trick is to reduce the backpressure as much as possible without making the pipe too large. That is to keep the exhaust velocity as high as possible with as little restriction as possible.

This is done by using mandrel bends instead of crush bends and increasing the pipe size to the sweet spot where there's less backpressure but velocity does not start to fall off.

Usually, manufacturers build the exhaust cheap. This means it's very restrictive. With these cars, Mazda did a good job. It already flows well so there's very little room for improvement.

With a restrictive muffler, they may add a larger pipe to compensate so simply removing the muffler may degrade performance. Depends on how it's built. If the pipe is sized right, you'd be removing considerable restriction caused by the exhaust.

Not quite as simple as you thought I'm guessing.
Thank you for the incredibly detailed response! I guess now I will juggle with either getting the smaller Corksport exhaust as to not go to large, or I might still consider a muffler delete I will just need to research others who have tried it.
 

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Because after researching the racing beat, a video I managed to find made the car sound exactly the same, and it seems pointless to spent $500 on a system that will make your car sound the same with no benefits...
I have been using the Racing Beat catback on my 2018 2.5L sedan for over 2 years and am really happy with it. The volume is a little louder than stock, but the tone is undeniably lower and throatier than the stock muffler. The YT video you watched (likely the one with the red hatchback) doesn't capture the sound difference well. Nonetheless, if volume is what you are after, go for the Corksport. However, I read a post from a 2018 sedan owner here that it drones so badly on the highway, he wound up selling it. That is why I went with RB.
277916
 

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With these cars, if you're spending the money on an exhaust it's because you like the noise. Not much power to be gained.

Have to say I was pleasantly surprised to see mandrel bends the first time I got under my car.
 

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Dont lose the back pressure . As zero_G mentioned. Losing all back pressure would mean no restrictions from Header (remove main cat, remove mid cat , remove muffler) and straight pipe it. No back pressure can mess up your sensors unless you remapp the ecu to take all that into consideration.

After Dyno with Corpsort CAI, and cat back exhaust with an OV Tune ..added 48 HP . Although i cannot remember if the SR lightwight pulleys were installed (extra 4 hp) This is with the non sky 2.0L
 

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Exhaust :

Catback Exhaust:

CORKSPORT Power Series Exhaust(Available at CorkSport Mazda Performance - 360-260-CORK)
2.5L and 2.0L Sedan and Hatch

Racing Beat Power Pulse Exhaust(Available at Racing Beat - Mazda Performance Specialists)
2.5L Hatch Only

Magnaflow (Available at MagnaFlow Exhaust Products - For Trucks, Suv's, American Muscle, Diesel, & Sport Compact Vehicles)

Thunder ] (Automotive Header, Muffler Manufacturer – Thunder Exhaust System Co., Ltd. contact protephile on mazda3fourms.com or email [email protected])
Mid-pipe and Axle-Back 2.5L Sedan???Hatch??? Need more info here

Axle Back Exhaust
Borla Available at (Stainless Steel Rear Section | 11786 | Mazda 3 2.3L 4cyl - BORLA - The World's Most Winning Exhaust)
MazdaSpeed 3 Stainless Steel Rear Section P# 11786

Racing Beat Power Pulse Exhaust(Available at Racing Beat - Mazda Performance Specialists)
2.5L Hatch P#71208
2.5L Sedan P#71207

HKS makes an exhaust
https://www.hks-power.co.jp/en/produ...ffler/db/11193
 

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Dont lose the back pressure . As zero_G mentioned. Losing all back pressure would mean no restrictions from Header (remove main cat, remove mid cat , remove muffler) and straight pipe it. No back pressure can mess up your sensors unless you remapp the ecu to take all that into consideration.

No, its just the opposite. You want no restrictions. Reversion, or "back pressure" as it was called years ago, is a very bad thing for modern engines. Scavenging, or the vacuum action between exhaust pulses that pulls the spent gases out of the combustion chamber, on the other hand is what you want.
The SA-G has a system that is not restrictive at all. If you were to change the system to a more restrictive aftermarket design you will lose power. The header is very efficient at extracting hot gases from the cylinder (scavenging), and the exhaust system moves them away quickly through pulse management (no reversion) so there is less heat build up in the combustion chamber. A more restrictive system means less hot exhaust gasses being extracted and more heat build up. More heat means more prone to knock, more knock means less timing advance, which in turn means less power.
On the other hand, you don't want the exhaust gas velocity to drop because the piping is too large as this will also reduce exhaust scavenging. If it does, same scenario - less extraction, more heat, less power. So, what you want is a properly designed free flowing system that has the correct pipe diameter for the required exhaust gas velocity and to manage the exhaust pulses in a controlled fashion so that there is no reversion. In other words, a system tuned to the requirements of the engine.

After Dyno with Corpsort CAI, and cat back exhaust with an OV Tune ..added 48 HP . Although i cannot remember if the SR lightwight pulleys were installed (extra 4 hp)
Full disclosure - The L engine in the 2012 Mazda 3 is not an SA-G motor, and doesn't respond to tuning in the same manner.....
 

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Dont lose the back pressure . As zero_G mentioned. Losing all back pressure would mean no restrictions from Header (remove main cat, remove mid cat , remove muffler) and straight pipe it. No back pressure can mess up your sensors unless you remapp the ecu to take all that into consideration.

After Dyno with Corpsort CAI, and cat back exhaust with an OV Tune ..added 48 HP . Although i cannot remember if the SR lightwight pulleys were installed (extra 4 hp)
Did you read anything I wrote up there?
 

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Did you read anything I wrote up there?
I zoomed thru it .
I gathered that a little back pressure is a good thing. ... The right size pipe is large enough to breathe well but small enough to create a high exhaust flow. Too big an exhaust pipe ..over 3.5 inches on smaller engine does not help on smaller displacements......All of this depends on things like tubing length, exhaust pipe diameters, the timing of the pressure waves, and other factors like inertial scavenging, velocity of exhaust vs pipe width.
Here is a great simple video about it : Do vehicle exhaust systems need back pressure?.


@arathol
Correct ...the SA-G 2.0 & 2.5 does not respond to tuning as well as predecessor 2.0L lower compression engine.
The SA-G has been tuned for maximum fuel efficiency and trying to pull more HP from it with reduce that fuel efficiency simply speaking. Problem is increasing HP and keeping the same power/hp/torque oem band. Lose at the bottom gain at the top. The MX5 ND 2.0L sky can be tuned and supercharged and reprogrammed (Ecutek) to gain the extra 80-100whp ...but im not sure if with the OEM headers and exhaust.
 

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Funny thing.. OV Tune added HP and torque AND a few extra mpg on 91 octane gas.. based on the avg mpg displayed by the car. I can only use 91 or higher octane now though, but the cost just about balances out with the improved gas mileage from the tune.
CK
 

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Funny thing.. OV Tune added HP and torque AND a few extra mpg on 91 octane gas.. based on the avg mpg displayed by the car. I can only use 91 or higher octane now though, but the cost just about balances out with the improved gas mileage from the tune.
CK
It's possible. More advanced ignition and cam timings would be more thermally efficient, but would require high octane fuel. Think of it as you're now able to make good use of premium fuel. Most people who dump it in their tanks are wasting it.
 

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Ok so came across these on the ebays??


Obx header system. Not at all like the factory mazda header.


Cat back system


What y’all think about obx’s quality and if these parts are at all any good?


Sent from my iPhone using Tapatalk
 

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Nope, not at all like the OEM header....... just some pipes welded into a header like object....for under $400 don't expect much. OBX stuff is from what I have seen in the past a "low cost alternative" to the parts they are copies of.....

OBX advertisement quote-
Replace inefficient factory cast log manifold
Cast log manifold? LOL... The Mazda 3 already has a very good long tube header thats pretty hard to beat....
 

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Maybe go OBX headers / cat back for non sky engines. I tend to try to stay away from china made stainless.
I installed a china made stainless steel high flow cat from Yonaka and exterior is already rusty red/rose looking compared to the Corksport stainless exhaust
and MSDS headers ... both look brand new after 3 years. Not sure if stainless cat is a same stainless steel on exhaust components
 
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