[JoeMini]

From what i have read about Mustang dynos is that they usually read about 18% less than dynojet which most manufacturers numbers are from.

132 whp which should be around 108 on a mustang dyno and about where you are now .
With a higher flow exhaust (no cats on the header) you should be bit more than oem.

Are you sure the OVT tune got mapped ?

 

[JoeMini]

Assuming the header does flow better.....
Chances are even though the header looks like the OEM part, its more restrictive, even without the cat. There is more to it than making it look like the OEM part.



So if the first graph is before the headers were installed, and the second one is after, you've lost 23 hp and 27 ft/lbs.....😩
You sure thats right?

Hey @arathol could it be possible you have too less restiction / too much flow / exhaust is too big on the heads and hits the rest of the and its like it slam a wall at the mid and end as it tries to funnel the exhaust out

 

[JoeMini]

Well, yeah, if the header diameter is not right it could significantly affect the exhaust flow. Any change in diameter is a possible restriction point, going either larger or smaller. You need to get the whole exhaust system end to end to function as a unit. That means the right length and diameter for proper pulse timing and scavenging. Sticking headers that have 2.5" pipe on a 2.25" system can cause problems.
Another possibility that not many consider is the weld quality on the headers. The welds might look good on the outside, but what about inside? If the bead has penetrated 100% through the pipe, there could well be slag and all sorts of nasty stuff on the inside of all those joints to interfere with the exhaust flow. You might be surprised how much of a difference this can make.

Cool Thanks your the best !

Also to consider is getting the headers ceramic coated. This also increases exhaust flow (no need to titanium warp) keeping heat inside headers, increases scavenging /flow .. but also a complimentary effect..is it keeps engine bay cooler too.
Also i only found out recently .. the corksport catback i had installed had what looked like 2 resonators (one was actually void , thus potentially slowing flow.. going from 2.25 inch to 4.5 inch x 7 inch void to 2,25). Had it replaced with a proper vibrant resonator) . Every little bit helps.

 

[JoeMini]

OBX Header Fits For 2014 thru 2021 Mazda3 Axela Skyactiv 2.5L PY-VPS SKYACTIV-G | eBay

2014-2021 Mazda3 Axela Skyactiv-G 2.5L PY-PVS. OBX RACING SPORTS. OBX Racing Sports™ 304 Grade Stainless Steel Header. OBX Free-flow High Performance Header will help these high-powered engines @ low/high RPM, without causing carbon build-up from an OEM Manifold Design!

www.ebay.com

Hmm.. the price has me a little concerned.

Anyone used OBX products before?
CK

I have used OBX for silicone racing radiator hoses.
Those headers look like the MSDS headers i have (without ceramic coating) ... Your low end torque will drop and HP top end will increase.
Sky OEM header are there to gain max low end torque,
MSDS - Exhaust Systems pricer than obx but made in california and ceramic coated

 

[JoeMini]

Yeah.. they look off.. OEM seems to be a winner.

Wasn't Corksport supposed to release one?
CK

I think they realized in the end that there were no real gains

 

[JoeMini]

They boasted 25 hp gain I think.. but losing the second cat caused a permanent CEL. Not good..

That post about the Heavily Modified 18 3 has one of their beta model headers on it.
CK

Yes ..i saw
Adding or removing or swapping 2 for 1 larger and/or highflow cat will affect OEM parameters either way. Need to reprogram.
that's when OVT / VF Tuner comes into play to be able to change the CEL code parameters or even turn that CEL from appearing on the cluster.
CA emissions measurement a bit different that here ( here on newer cars if a visual that no CEL present). There they measure tail emissions?
Its usually the 2nd O2 sensor that is the culprit on these when changing the exhaust flow