Testing & Validation: CorkSport 2.5L SkyActiv Race Header

Over the past few months, we’ve been teasing you with tidbits of info on the CorkSport Race Header for the Mazda 3 2.5L SkyActiv-G in the GEN3’s. Today’s blog is a big one as we go through the testing we performed on the header and share some results, including power! Before we get too deep though, be sure to get up to speed with a breakdown of the OEM header and our design goals for the CS header.

mazda 3 skyactiv header
2014+ Mazda 3 Header Installed

Addressing Underhood Heat

In our previous blog, some of you keen-eyed individuals were asking about underhood temperatures with the ram-horn style CorkSport header. Well, we went through testing to ensure everything will function as before when the new header is added. We’re happy to let you know that we saw very similar under the hood temperatures as the OEM header. As a double check, we applied some temperature sensitive stickers to some areas near to the CS header, as shown below. These stickers will fill in with color if a temperature listed is reached. While these ended up reaching higher temps than with the OEM header, no areas are at risk of damage or malfunction. Furthermore, both the CorkSport racecar and our beta tester have run the 2014+ Mazda 3 race header at the track with no issues with overheating, power losses, or engine bay damage!

2.5l SkyActive Race Header testing
2.5l SkyActive Race Header testing with temperature sensitive stickers

How Does The Header Sound?

Before we get into the really good stuff, let’s go through a side effect of freeing up the headers on any engine: volume. We tested the Mazda 3 SkyActiv race header with multiple different setups: OEM cat back, CS 60mm cat back, CS 80mm cat back, and straight pipe. The race header on an OEM cat back is something that will not likely be used often (who runs a racecar with a stock exhaust?) but offers some nice growl and extra volume over the OEM exhaust. Both the CS 60mm and 80mm exhausts sound fantastic, with the 80mm being louder and having higher power potential than the 60mm. Even so, the 80mm is not uncomfortably loud and could be daily driven if full catalytic converter deletes are street legal in your area. We cannot recommend the straight pipe though. It is extremely loud and very uncomfortable. If you want a tease of sound with the 80mm cat back, check out our feature on our beta tester’s car in the video below.

80mm Cat Back with the 2014+ Mazda 3 Header!

The SkyActiv-G Race Header Adds Power

Full Race Header for the Mazda 2.5l SkyActiv Engine
Full Race Header for the 2.5l SkyActiv Engine

Alright, I’ve kept you waiting long enough, let’s talk power. The 4-2-1 design is very evident in our tests, as we did not see huge gains at peak WHP/WTQ. We did see very good gains throughout the midrange. From 2000RPM or lower all the way up to about 5300RPM we made 4-8WHP and 5-15WTQ. On our beta tester’s car with a good tune and supporting mods, this meant 194WHP and 226WTQ on 91 octane pump gas. The graph below shows a direct comparison of a 2016 Mazda 6 with a CS short ram intake, CS 60mm exhaust, and the same tune with and without the race header. Keep in mind, there is more optimization to be had with tuning with the header installed, and greater gains with an 80mm exhaust. The midrange gain may not seem like much but is extremely noticeable when driving the car.

Mazda 6 Race Header Dynograph
Comparison of a 2016 Mazda 6 with a CS short ram intake, CS 60mm exhaust, and the same tune with and without the race header.

That’s about it for our testing and validation blog. Next time you’ll hear about the CorkSport Race Header for the 2014+ Mazda 3, it will be released! Be sure to stay tuned to all the CS channels if you’re interested in being one of the first to pick one up.

-Barett @ CorkSport

P.S. We noticed a lot of you asking if this header will fit the auto transmission or 2.0L. The automatic transmission is 2-3” larger right where the lower section of the header sits, so for optimum pipe routing, we had to do away with automatic fitment. The 2.0L has a different bolt pattern and exhaust port spacing on the engine, so the 2.0L will not work with the CS race header either.

submit a product idea here if you would like to see automatic fitment, 2.0L fitment, or any other product for your car. The more submissions, the more likely we are to produce one so tell your car buddies!

Testing & Validation: CorkSport 2.5L SkyActiv Race Header
Article Name
Testing & Validation: CorkSport 2.5L SkyActiv Race Header
The 2.5L SkyActiv Race Header is coming for the 2014+ Mazda 3 and Mazda 6 -- hear the beautiful sound and learn the details behind the design!
Publisher Name
CorkSport Mazda Performance
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19 Replies to “Testing & Validation: CorkSport 2.5L SkyActiv Race Header”

  1. The header only works with Manual Transmissions. The header is set to be released on 7/4

  2. While a race header is nice, I wish it were a street legal header with a high-flow cat that fit both manual and auto 2.5s. (Yes, I submitted the product idea)

  3. This will fit your car only if it’s a manual transmission and is the 2.5 liter skyactiv-G engine

  4. Thanks for making this product. I have a 2.5L manual transmission GT model and I’m very interested in it. I couldn’t live with the CEL being on all of the time though.

    Are there any plans to make one that has a cat and a downstream O2 sensor? i.e. street legal. I already submitted a request for one, but I guess I can send another.

  5. Man, that looks amazing and I see that there isn’t an option for the A\T (for now). I’m looking forward to adding some more quality products from CS and others.

  6. I haven’t looked under the hood of my car(and probably should), but how difficult of an install is this with the majority of the header being behind the engine? Any specifics you can give on how it goes in and what may have to come off to install?

  7. Hey Ryan,

    In terms of difficulty, we rank this a 4/5 – 5 being the most difficult (we would rate a five on something like engine internals). We’ll have our official installation instructions ready soon, so keep an eye out on the product page for the details that you need!

  8. Will there be one for the 2.0? Submitted a product request already. Hopefully there is enough demand 🙂

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