exhaust diameter for the V6?

[vnzbd]

Had some thoughts/questions on the exhaust diameter for our V6s. Ford goes with the 2.25" as well as Borla. It is my impression that Borla does as much if not more R&D on their products. Their claim is the exhaust diameter they use is the best for exhaust scavenging. Ford may have had this same thought. Borla also claims an average of 8-12 HP on most of their systems. When I did further research online for exhaust diameter vs. HP everyplace read that 2.25" was right in line for a 300HP (up to 350) engine.

I like many here have installed the GT exhaust at 2.5" with H-pipe). I can't say that I got any gains but am concerned about any possible losses. Our cars have a decent amount of power and I want to keep it all.

Has anybody run any dynos or have any other insight or feedback to this?

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[cyclonetron]

I had the GT catback installed with Roush ab's for a while. I then switched to the Borla Atak 2.25". I did notice more torque in the low end. Not a huge difference, but I did notice it right away.

 

[USMCtoARMY]

This. Exhaust by themselves dont really offer gains unless u go catless and tune.

 

[MidwayJ]

I initially added an axle back to the stock V6 exhaust, then replaced everything with the stock GT catback. I noticed no difference in performance with either change. I suppose it's possible there was a small change I did not notice. It did not occur to me there could be a difference, so I was not looking for it.

This reminds me, in the thread about developing the Solo Performance catback, there was a comment from Solo that "this engine likes a certain amount of back pressure." That seems to suggest the 2.25" pipes could be beneficial if that's where additional back pressure is coming from.

 

[USMCtoARMY]

Well yes and no. Just remember if you boost you will want 3 inch. You won't notice a difference in stock diameter vs 2.5 vs 3. Trust me nothing. Your butt dyno will say different but its the noise. A better free flowing exhaust in combo with headers and tune will provide best gains.

 

[vnzbd]

Cyclonetron, That was my concern was the loss of the low end torque. Interesting that you felt it right away. Based on your exhaust swap I would not think you were just caught up with the exhaust tone. I am not a racer by any means and the majority of the time I am under 4k rpms. I would like to see and actual dyno curve to see where the actual gains or losses actual are. I believe the larger diameter exhausts may help with the HP at a much higher rpm that I am hardly ever at.

 

[vnzbd]

USMC, quite the list of mods you have! The Solo exhaust looks very interesting. Why did yo opt for the 3" over the 2.5"? Are you planning on boosting?

 

[USMCtoARMY]

USMC, quite the list of mods you have! The Solo exhaust looks very interesting. Why did yo opt for the 3" over the 2.5"? Are you planning on boosting?

Thanks, modding becomes an addiction lol. It started out three inch mid pipes back because I got a good deal on the SOLO performance system off a GT owner. I stayed three inch, because yes I am boosting. I have ran stock diameter, 2.5 diameter, and three inch diameter....literally zero difference. Just felt faster aka butt dyno. Again, CAT deletes, headers, and tune is where you will feel the most benefit with an exhaust system (ported manifolds help too).

 

[Stanley]

USMC, quite the list of mods you have! The Solo exhaust looks very interesting. Why did yo opt for the 3" over the 2.5"? Are you planning on boosting?

I have a Solo cat back exhaust , in the box ready for install (v6 model, 2.5 in) .... hopefully soon ( when time allows-) anyways i let you folks know how it goes, and any thoughts.
Otherwise 100% stock car. Doing it mostly to get more sound. Hopefully it adds a bit of juice to the ride as well.
Worth mentioning.... i cant speak to the quality or performance of the unit because its been in the box for around a yr...unopened in garage. But when i phoned and ordered it...i spoke directly to the owner of the co. ....Jeff ? Anyways i think it was him. He gave me a solid , fair price and the exhaust was on my doorstep the next day.

 

[USMCtoARMY]

I have a Solo cat back exhaust , in the box ready for install (v6 model, 2.5 in) .... hopefully soon ( when time allows-) anyways i let you folks know how it goes, and any thoughts.
Otherwise 100% stock car. Doing it mostly to get more sound. Hopefully it adds a bit of juice to the ride as well.
Worth mentioning.... i cant speak to the quality or performance of the unit because its been in the box for around a yr...unopened in garage. But when i phoned and ordered it...i spoke directly to the owner of the co. ....Jeff ? Anyways i think it was him. He gave me a solid , fair price and the exhaust was on my doorstep the next day.

Did you get the full exhaust with the resonator replacement? If not dump that factory suitcase resonator.

 

[Stanley]

Did you get the full exhaust with the resonator replacement? If not dump that factory suitcase resonator.

Honestly, no idea ...

Is the resonator after the cats.. its a cat back system, i believe it comes with an x-pipe... would that, in turn mean removal/elimination of any resonator?
Never crossed my mind. The owner told me the system sounds dynamite, and I'm looking fwd to it. Had a 90 5L sedan. That stock exhaust note will forever be unmatched-)
But these 3.7s have a great sound also...just needs more volume.
The Solo 3.7 videos on YouTube sound pretty darn good... and the one is an auto. I expect a good bark from our stick shift car-)

 

[MidwayJ]

Honestly, no idea ...

Is the resonator after the cats.. its a cat back system, i believe it comes with an x-pipe... would that, in turn mean removal/elimination of any resonator?

Yes. Since it's the cat back it will replace the stock resonator. By the way, letting it sit in the garage for a year without installing is unacceptable around here!

 

[Stanley]

Yes. Since it's the cat back it will replace the stock resonator. By the way, letting it sit in the garage for a year without installing is unacceptable around here!

I hear ya, waiting for my buddy, who is a great mechanic, w garage and a hoist...to dial it in. Want to get under the car myself and check out the suspension..can't believe how well the car handles at speed. For a base model. I like the 55 sidewalls on the 17inch rim, eats up bumps, cushy ride, and i dont corner too hard, but when i do the car seems pretty darn planted... has a great stance on the stock rims and tires. The motor is set back quite a bit also i notice... Good balance. What a value these cars are. I really enjoy driving it daily. 23-24 mpg.... 80%hwy driving..
And thats w a pretty aggressive throttle foot. I think its bang for the buck champ. Sweet shifting car, cant wait for it with new exhaust, and added sound, shall be even more fun we hope-)

You folks with the tuners, 3.73 rear gear, exhaust, rims, tires, suspension mods...must have a coupe that seriously rolls out.
These cars are a bit of a boat, wish it was 400-500lb lighter, like the old LX foxes..mine had zero options, no pwr doors, no pwr windows, no air, no cruise. Had a button for the trunk in the glove box...thought that was a great std feature-)....but that LX still weighed around 3100lbs i believe...
....but comfort , irs, and safety come at a price. 3500lbs and change. Seems its inline with all cars, thats just the story these days.

Yes. Since it's the cat back it will replace the stock resonator. By the way, letting it sit in the garage for a year without installing is unacceptable around here!

 

[Nagare]

Yes. Since it's the cat back it will replace the stock resonator. By the way, letting it sit in the garage for a year without installing is unacceptable around here!

You must not know @USMCtoARMY's situation then! He's hoarding parts for years it seems!

And my car moves...but I also don't help with that because I've got heavy 20s and a speaker box in the trunk, no weight reduction at all for me. If I seriously wanted to go faster, I would get rid of my subs, rip out the rear seat, remove the spare tire, and put on some much lighter wheels (mine were 31.8 when I weighed them, SVE R357 is 23.2 - that's 35lbs saved there).

 

[MidwayJ]

You must not know @USMCtoARMY's situation then! He's hoarding parts for years it seems!

Haha. Well, being separated from his Mustang half a world away might deserve some consideration.

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