2.5" Exhaust Guidance

[Ecto1]

So I'm considering an upgrade to 2.5" cat back exhaust + 3" down pipe and I could use some guidance from those who own one. However... I have the ragtop with the associated rear chassis brace PLUS I have the Curt trailer hitch installed. Just to make things complicated enough. I also want as little noise as possible. I'm not looking to replace the exhaust for sound reasons but to get as much heat out of the engine as possible as fast as possible. There are 3" exhausts which would be more suitable but I'm sure they won't clear the chassis brace. They'd also be way too noisy.

I like the concept of the ARK GRiP exhaust "J Pipe" for passive noise cancelling but the hitch is in the way. It may be in the way for any of the aftermarket mufflers but I don't think so. The stock mufflers fit just fine, but only just.

The COBB system is interesting because it has a 10" resonator just after the down pipe. None of the other systems I've seen have the resonator. But the COBB system uses flange connectors just behind the rear axle, right where the chassis brace has to go. So I'm not sure if the COBB flanges will clear.

The Hooker system might also minimize the noise from the free-er flowing exhaust but it's hard to tell from the videos.

I don't care how noisy it is outside the car, only how noisy it is INSIDE the car (what some of the manufacturer's call "drone"). I've had my fill of noisy low restriction exhaust over the years. I want peace and quiet. I wish there was an electronic noise cancelling system but I haven't seen one yet. Nor do I want to pay for one.

So I guess I'm looking for the quietest 2.5" cat back system. Quietest inside the car.

Opinions from those running the various 2.5" systems welcome.

Thanks.

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[ElAviator72]

Too bad you have a 'vert, the MBRP is as sweet as it comes.

I've often wondered why the MBRP is not compatible with convertibles

 

[Ecto1]

ElAviator

Thanks for the reply. I've read on ecoboost.net that one or two of the kids there have installed the MBRP cat back on their 'verts. Takes a little finagling but they've been successful.

I believe the MBRP is a 3" system. Is that correct? If so I wouldn't expect it to clear the chassis bracing without heavy modification. It's REALLY tight back there. I suspect that to fit a 2.5" system I'll have to add fender washers between the chassis brace and the body to give an 1/8" to MAYBE 3/16" additional clearance between the brace and the pipes. I don't think that will have too much impact on the structural integrity of the brace. A minor risk but I might be willing to take it. But more than 3/16" washers seems too risky. And I think that's what it would take to clear the 3" pipes. Assuming they are formed so that they route through the OEM channels in the brace. It seems like it MIGHT be possible.

Also, does the MBRP connect to a 2.25" downpipe? Or did you need a 3" downpipe with a 3" fitting to connect to the MBRP pipes as well?

Thanks.

 

[Buldawg76]

MBRP connects to factory 2.25" DP using factory saddle clamp. Not sure about clearance on braces.

BD

 

[K4fxd]

Are there any pics of these convertible braces?

 

[Ecto1]

K4fxd, check out the images in this thread...

https://www.mustang6g.com/forums/th...-exhaust-with-that-pesky-extra-bracing.66774/

 

[Buldawg76]

K4fxd, check out the images in this thread...

https://www.mustang6g.com/forums/th...-exhaust-with-that-pesky-extra-bracing.66774/

If you read post #8 in the linked thread in your above post the member states, the MBRP does fit his vert without issues with braces.

BD

 

[Ecto1]

The post #12 in the same thread claims that 3/8" washers were needed to fit the MBRP exhaust. That seems too risky to me. 3/8" of thread bite lost for the washers. Maybe if a 1/2" longer bolt is available & will thread in without bottoming out ... I'll have to examine things back there and scratch my head for a while before I'm ready to jump in.

 

[Buldawg76]

The post #12 in the same thread claims that 3/8" washers were needed to fit the MBRP exhaust. That seems too risky to me. 3/8" of thread bite lost for the washers. Maybe if a 1/2" longer bolt is available & will thread in without bottoming out ... I'll have to examine things back there and scratch my head for a while before I'm ready to jump in.

Here is another option for you to consider for an exhaust on your vert.



BD

 

[Andrew@Lethal]

I would get a MBRP and get it to fit. Nothing beats the sound of that MBRP race growl!

MBRP 2015-2021 Mustang 2.3L Ecoboost Aluminized Race Series Cat-Back (Polished Tips) - S7275AL

 

[Ecto1]

Buldawg76. I considered a custom, or semi-custom exhaust, briefly. Unfortunately there are NO custom exhaust shops in the county where I live. None. The closest one is 75 miles away. No idea if they are good, bad, or indifferent. They're just the closest one. I'd have to put up with serious aggravation if I go down that path.

I'm also fascinated by the Helmholtz resonators. I'd like to find a car with the ARK GRiP system so I can hear it from the inside the car. I doubt there are many custom fabricators that can engineer a "J pipe" for any car that comes in. But I'd still like to hear how they sound. If they work as well as the ARK ads claim I think that would be the way to go. Probably the MBRP exhaust plus a custom "J pipe". But I doubt that is going to happen.

Thanks. A custom exhaust is probably the best option for the ragtops if you have a high quality custom exhaust shop near you.

 

[Buldawg76]

Yep, quality exhaust shops are hard to find in todays world for sure. You could go with the MBRP and just flatten the pipe where it passes over the rear bracing to not have to need the spacers/washers possibly since three-inch pipe will not suffer much flow restriction from a little flattening. Just a thought.

I love the sound of my MBRP race system, slight drone in the 2000-2200 rpm range but very tolerable on the highway for me.

BD

 

[Ecto1]

Buldawg76 ...

Thanks for the suggestions. I'll keep puzzling over this for the time being. Looks like I'll have to make my peace with some custom work in order to get a free flow exhaust installed in the car. Either by banging on it with a hammer myself or schlepping over to a custom shop - assuming I can find one. Not the answer I was hoping for but it seems unavoidable.

Thanks everyone.

 

[Buldawg76]

If you have access to a 6' vice that is what I would use to flatten the pipes on the MBRP system versus using a hammer. Just mark the pipe with a sharpie where it needs flattened and use the vice to squeeze it for the required clearance.

BD

 

[Ecto1]

BD ... I do have a vise. (6" though, not 6') Not sure it would work to deform the stainless pipes or not. I could certainly give it a try. Wish I still had the exhaust pipes from my truck. Would make a good test case. I'll have to see if I can find some cheap pipes to try that with. Hmm.....

Thanks.

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