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Discussion Starter · #1 ·
hey guys, i was wondering, has anyone removed the 2nd cat on their 3rd gen? im thinking of doing it but i dont want to lose hp/torque. i know the corksport catback removes the second cat, but idk if their res in their midpipe is special for creating backpressure or something. so, my question is, will i lose torque in the lower rpms if i delete the second cat? also, will i get a CEL if i delete the second cat?
thanks!
 

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2018 Mazda 3 GT
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It says on the Corksport website that removing the 2nd cat will not throw a CEL, but that it may not be emissions standard legal... or something like that.

I plan on buying their cat back exhaust, once I get my tax return. :)
CK
 

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Discussion Starter · #3 ·
im not worried about emissions, where i live theres no smog test. i just dont want my car to lose torque if i delete the second cat.
 

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Discussion Starter · #5 ·
ive seen that post, and i would replace the resonator with a vibrant one, tho i do want to delete the second cat without affecting performance negatively.
 

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I have the corksport cat back and would definetly recommend getting the mid pipe that deletes the cat. I get more power out of my car and it makes my axle back 50% louder.
 

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Discussion Starter · #7 ·
i already have an ultimate racing axleback, but i want to do a custom midpipe, since the midpipe of corksport is quite expensive plus shipping to mexico would be aprox 150 dollars.
 

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I have the corksport cat back and would definetly recommend getting the mid pipe that deletes the cat. I get more power out of my car and it makes my axle back 50% louder.
Louder is not better. Ever. I'm not sure 50% louder is any sort of an improvement. :surprise:

 

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2014 Mazda 3 i Touring 6MT 2.0L
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Louder is not better. Ever. I'm not sure 50% louder is any sort of an improvement. :surprise:





The CS midpipe is incredibly loud compared to stock or a resonator delete (not recommended per actual documented torque loss-VoodooJeff dyno’d 14ft/lb reduction). While I have the CS midpipe, I’ve also added a Vibrant Ultra Quiet resonator where the cat was originally, granted I’ve deleted the primary cat by switching out the stock exhaust manifold with OVT’s 4-2-1 header.


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i already have an ultimate racing axleback, but i want to do a custom midpipe, since the midpipe of corksport is quite expensive plus shipping to mexico would be aprox 150 dollars.


Even though I have the CS midpipe, if I were to redo everything, I would go custom mainly d/t cost. The CS midpipe can be easily replicated-just one long bottle style resonator and a bung, not to mention 2-piece vs single.


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Discussion Starter · #11 ·
so if i add a resonator where the 2nd cat was, i wont lose torque? (ill also add another resonator where the og resonator was)
 

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Maybe, maybe not. Depends on the design of the part. You really need to be very careful when changing the exhaust on these cars. The header and exhaust system have been carefully designed to provide maximum exhaust gas extraction to enable the engine to run at a 13:1 compression ratio on 87 octane gas without self destructing. Changing the diameter of the pipes changes the flow velocity and its possible to get some turbulence at the points where the diameter changes. Either one or both can actually impede the exhaust flow. This means that more spent gases will remain in the cylinder, raising internal temperatures and causing pre ignition or knock. The sensors will pick this up, pull the timing accordingly and you end up with less power. Bottom line, if you are going to start changing parts, make sure they have been tested and proven to work with the SkyActiv engine.
 

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