worthwhile performance gains from 2.5" exhaust to 3"

[Robert M]

I

Ya, sorry, I should have read your post more carefully.

On a side note....the outlet on the stock 2010 manifolds is only 2"...its amazing we get as much power as we do.
View attachment 1629394

I agree, the 725, 750, 800 and 850 Super Snakes, ALL 50 state emissions legal, ALL retaining their oem cast iron log manifolds and oem catted exhaust with only a catback add.

The FRPP shorty's are a little bit larger at the outlet, I believe I measured 2-3/8".

R

 

[PM-Performance]

Ya, sorry, I should have read your post more carefully.

On a side note....the outlet on the stock 2010 manifolds is only 2"...its amazing we get as much power as we do.
View attachment 1629394

Not sure if the 2010 is like the 07-09, but yea looking at the design for them, I am quite surprised they went that way. They look soooooo restrictive, which is why people see LARGE gains from getting rid of them. Not sure why Ford thought it made sense to put truck style manifolds on their flagship Mustang

 

[VNMOUS1]

What kind of power will 2.5 support?


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1000+

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[Robert M]

Not sure if the 2010 is like the 07-09, but yea looking at the design for them, I am quite surprised they went that way. They look soooooo restrictive, which is why people see LARGE gains from getting rid of them. Not sure why Ford thought it made sense to put truck style manifolds on their flagship Mustang

I would guess that tight space and the assy. line install flow is the reason why they went with a compact/close cast iron manifold. I have not heard anyone talk about headers being an easy install, not even the shorty's.

R

 

[PM-Performance]

I would guess that tight space and the assy. line install flow is the reason why they went with a compact/close cast iron manifold. I have not heard anyone talk about headers being an easy install, not even the shorty's.

R

While that makes some sense, how do they drop the motors into these on the lines? Without the front clip on? Or just drop in from top and shimmy in? Either way its a hell of alot easier without the motor in the car is my guess.

 

[builttodrive]

They are preassembled and attached to the Kmember and come up from the bottom.

 

[builttodrive]

I would venture that there would be an increase but just didn't know if it was worth the money and time at this stage. Other cars we build through our shop typically have larger displacements and are NA but respond very well to the increased exhaust size and show decent gains. Like I mentioned I like the deeper note of the 3" generally but I know it will increase the volume also and I would be looking at probably doing something different with the mufflers as it's already pretty loud if I'm getting after it at all and I wouldn't want it louder in that regard.

 

[Robert M]

Not sure if the 2010 is like the 07-09, but yea looking at the design for them, I am quite surprised they went that way. They look soooooo restrictive, which is why people see LARGE gains from getting rid of them. Not sure why Ford thought it made sense to put truck style manifolds on their flagship Mustang

^^^^^and one more add to your "soooooo restrictive" mention above................We are back to.....Why would Ford/SVT engineers upsize the pipe from 2.5" to 2.75" while retaining those restrictive manifolds if the manifold outlet is only 2"? What benefit would a 2.50" to 2.75" make? They apparently, through testing found a benefit to redesigning the exhaust system to the larger 2.75" size at the 550HP level....

......and then take a 3" long tube header collector and taper it down to a 2.5" exhaust system........Say What?!?!?

R

 

[Robert M]

I would venture that there would be an increase but just didn't know if it was worth the money and time at this stage. Other cars we build through our shop typically have larger displacements and are NA but respond very well to the increased exhaust size and show decent gains. Like I mentioned I like the deeper note of the 3" generally but I know it will increase the volume also and I would be looking at probably doing something different with the mufflers as it's already pretty loud if I'm getting after it at all and I wouldn't want it louder in that regard.

It can't be said that other year Mustangs have not had factory shorty's, but then again most were crimped at some points and somewhat restrictive also. One other point.......The manifolds probably easily passed 50 state emissions requirements, tubed headers, maybe not all 50 states?

R

 

[Robert M]

They are preassembled and attached to the Kmember and come up from the bottom.

Yes, I was thinking they came up (or were stuffed) from the bottom, but I was not sure how the assy. "in the car" would differ between manifolds and tubed headers?

R

 

[fullboogie]

^^^^^and one more add to your "soooooo restrictive" mention above................We are back to.....Why would Ford/SVT engineers upsize the pipe from 2.5" to 2.75" while retaining those restrictive manifolds if the manifold outlet is only 2"? What benefit would a 2.50" to 2.75" make? They apparently, through testing found a benefit to redesigning the exhaust system to the larger 2.75" size at the 550HP level....

......and then take a 3" long tube header collector and taper it down to a 2.5" exhaust system........Say What?!?!?

R

Because Ford's exhaust system supplier gave them a better deal on 2.75".

 

[Robert M]

Because Ford's exhaust system supplier gave them a better deal on 2.75".

That sounds like a good reason.....

R