Sponsored

mpeugeot

Outer Banks
Well-Known Member
First Name
Mark
Joined
May 14, 2021
Threads
17
Messages
7,299
Reaction score
13,558
Location
Texas
Vehicle(s)
97 Ferrari F355, 11 Ford F-150, 21 OBX 2D
Your Bronco Model
Outer Banks
So I installed the Flowmaster Axle Back Exhaust... My first impression was that it was way too loud at cold start... But then I realized I had forgotten to close the tailgate. LOL. That plus I was in between two walls and it was resonating off the concrete.

So I closed the tailgate, backed out from between the two houses and things were much more mellow. Now my big concerns were how loud was it really going to be and could I tolerate it on a 5-6 hour road trip at speeds from 65-85+ MPH (back to that in a moment) so I could put an additional fuel cell where the muffler used to reside.

Driving it around town, off and light throttle, it's anywhere from unobtrusive to throaty but certainly livable. Give it some throttle and it starts to sing, loudly, but it doesn't sound like a fart cannon or anything remotely import like - just louder and throatier. At all speeds, shifts were much more noticeable since you can hear the obvious change in the engine note (I drive in Sport Mode most of the time and it was interesting to see how long the Bronco really held the shifts), before the exhaust, I had to pay attention to notice the shifts... And purely by feeling, it remains smooth, but the engine tones give it away. All in all, it gets a passing grade from me around ton.

So it was off on my highway adventure from San Angelo to Corpus Christi - which normally involves a fuel stop around 1/2 way during the 365 mile trip due to the craptastic fuel economy my Bronco historically managed (usually about 16-17 MPG highway with the 33.5" Milestar Patagonia M/T's and stock exhaust). Switching back to the OBX stock tires had me at nearly 19-20 MPG, definitely not enough to make 365 miles without refueling.

The noise, while cruising from 65-85+ MPH was noticeable, but not excessively droning, it wasn't any more noticeable than the tire or wind noise - but it was there. It was never unpleasant or annoying and I drove the trip straight through... That's right, I drove it straight through WITHOUT needing to stop for fuel in a 2 door Bronco with a 16 Gallon Tank and room to spare. I maintained an average speed just north of 70 MPH despite a horrific accident and traffic jam in San Antonio which didn't help my average speed or fuel economy. I arrived with nearly 20 miles of range left and averaged just a shade over 23 miles per gallon with an average speed of 70MPH.

What that means for me is no longer really needing to add the fuel cell. There was some low end grunt and spool that clearly improved as well, but for $140, this exhaust delivered and then some. A 15% increase in mileage was not something that I was expecting from an axle back pipe.

IMG_20220413_151749.jpg


IMG_20220413_184202.jpg
Sponsored

 

Roll Sound

Wildtrak
Well-Known Member
Joined
Jul 3, 2021
Threads
29
Messages
1,481
Reaction score
2,112
Location
Hollywood
Vehicle(s)
2021 Wildtrack 2DR MIC OW, 2014 KTM RC8R
Your Bronco Model
Wildtrak
So I installed the Flowmaster Axle Back Exhaust... My first impression was that it was way too loud at cold start... But then I realized I had forgotten to close the tailgate. LOL. That plus I was in between two walls and it was resonating off the concrete.

So I closed the tailgate, backed out from between the two houses and things were much more mellow. Now my big concerns were how loud was it really going to be and could I tolerate it on a 5-6 hour road trip at speeds from 65-85+ MPH (back to that in a moment) so I could put an additional fuel cell where the muffler used to reside.

Driving it around town, off and light throttle, it's anywhere from unobtrusive to throaty but certainly livable. Give it some throttle and it starts to sing, loudly, but it doesn't sound like a fart cannon or anything remotely import like - just louder and throatier. At all speeds, shifts were much more noticeable since you can hear the obvious change in the engine note (I drive in Sport Mode most of the time and it was interesting to see how long the Bronco really held the shifts), before the exhaust, I had to pay attention to notice the shifts... And purely by feeling, it remains smooth, but the engine tones give it away. All in all, it gets a passing grade from me around ton.

So it was off on my highway adventure from San Angelo to Corpus Christi - which normally involves a fuel stop around 1/2 way during the 365 mile trip due to the craptastic fuel economy my Bronco historically managed (usually about 16-17 MPG highway with the 33.5" Milestar Patagonia M/T's and stock exhaust). Switching back to the OBX stock tires had me at nearly 19-20 MPG, definitely not enough to make 365 miles without refueling.

The noise, while cruising from 65-85+ MPH was noticeable, but not excessively droning, it wasn't any more noticeable than the tire or wind noise - but it was there. It was never unpleasant or annoying and I drove the trip straight through... That's right, I drove it straight through WITHOUT needing to stop for fuel in a 2 door Bronco with a 16 Gallon Tank and room to spare. I maintained an average speed just north of 70 MPH despite a horrific accident and traffic jam in San Antonio which didn't help my average speed or fuel economy. I arrived with nearly 20 miles of range left and averaged just a shade over 23 miles per gallon with an average speed of 70MPH.

What that means for me is no longer really needing to add the fuel cell. There was some low end grunt and spool that clearly improved as well, but for $140, this exhaust delivered and then some. A 15% increase in mileage was not something that I was expecting from an axle back pipe.

Ford Bronco Flowmaster Outlaw Series Axleback installed on 2.7 Bronco [Video Sound Clip] IMG_20220413_184202
Hmm, now I'm really curious about the mileage gains from this.
 

mpeugeot

Outer Banks
Well-Known Member
First Name
Mark
Joined
May 14, 2021
Threads
17
Messages
7,299
Reaction score
13,558
Location
Texas
Vehicle(s)
97 Ferrari F355, 11 Ford F-150, 21 OBX 2D
Your Bronco Model
Outer Banks
Hmm, now I'm really curious about the mileage gains from this.
I wouldn't have believed it without seeing it. Your mileage may vary... However, I was shocked. I would have called bullshit on just an axle back pipe having that much of an effect.
 

Roll Sound

Wildtrak
Well-Known Member
Joined
Jul 3, 2021
Threads
29
Messages
1,481
Reaction score
2,112
Location
Hollywood
Vehicle(s)
2021 Wildtrack 2DR MIC OW, 2014 KTM RC8R
Your Bronco Model
Wildtrak
I wouldn't have believed it without seeing it. Your mileage may vary... However, I was shocked. I would have called bullshit on just an axle back pipe having that much of an effect.
Funny, I was sort of calling BS on the HP gains too. Now I can't wait to put it in tomorrow!
 

Sponsored
OP
OP
killaz05

killaz05

Badlands
Well-Known Member
First Name
Charles
Joined
Jul 6, 2020
Threads
6
Messages
382
Reaction score
1,273
Location
Rockledge, FL
Vehicle(s)
2021 Ford Bronco Badlands 2.7 Sasquatch
Your Bronco Model
Badlands
Clubs
 
those bolts on the rear bumper, muffler bracket. I couldn't break them loose. I used an impact, regular ratchet, wrench w/ cheater; and those two wouldn't budge.
Should just be the clamp you have to loosen. The exhaust then slides out of the hangers. I used WD40 to help.
 

BlueOvalBandit

Badlands
Well-Known Member
First Name
Kenneth
Joined
Jul 13, 2020
Threads
2
Messages
738
Reaction score
2,454
Location
Anaheim, CA
Vehicle(s)
Tacoma
Your Bronco Model
Badlands
those bolts on the rear bumper, muffler bracket. I couldn't break them loose. I used an impact, regular ratchet, wrench w/ cheater; and those two wouldn't budge.
I think they're spot welded if we're talking about the passenger side ones. I had a couple wtf why won't this go moments and took a closet look. To me it looked tacked into place. Get a exhaust hanger tool for $15-20 and pop the hanger off and leave the bracket in place.

I just did a 12 hour off/on road ride with the 2.3l. It's not super loud (stereo on vol 9 can hear music clearly) but it does drone with windows up and decreases with windows down. It does sound nice on cold start and off idle.
 

Sponsored

mpeugeot

Outer Banks
Well-Known Member
First Name
Mark
Joined
May 14, 2021
Threads
17
Messages
7,299
Reaction score
13,558
Location
Texas
Vehicle(s)
97 Ferrari F355, 11 Ford F-150, 21 OBX 2D
Your Bronco Model
Outer Banks
I think they're spot welded if we're talking about the passenger side ones. I had a couple wtf why won't this go moments and took a closet look. To me it looked tacked into place. Get a exhaust hanger tool for $15-20 and pop the hanger off and leave the bracket in place.
I didn't look closely, but I hit it with an impact wrench that normally has no problem taking these off... They didn't budge, I will look again to see if mine are welded. I do have a new plasma cutter to try out... :D I did what you did, I popped the hanger off and left the bracket in place.

I just did a 12 hour off/on road ride with the 2.3l. It's not super loud (stereo on vol 9 can hear music clearly) but it does drone with windows up and decreases with windows down. It does sound nice on cold start and off idle.
At what speed do you get drone? I do get some drone with the 2.7 at around 60 MPH, but I rarely am under 70 MPH on the freeway, so it's a non-issue for me.
 

BWepps

Outer Banks
Well-Known Member
Joined
Apr 12, 2022
Threads
18
Messages
238
Reaction score
245
Location
Huntley, IL USA
Vehicle(s)
2022 Ford Bronco Outer Banks
Your Bronco Model
Outer Banks

mpeugeot

Outer Banks
Well-Known Member
First Name
Mark
Joined
May 14, 2021
Threads
17
Messages
7,299
Reaction score
13,558
Location
Texas
Vehicle(s)
97 Ferrari F355, 11 Ford F-150, 21 OBX 2D
Your Bronco Model
Outer Banks
Super interesting and I've been looking at the Flowmasters for quite a while. Don't quite want the sound of the Outlaw though, and I'm leaning towards the FlowFX Axle-Back Dual. Not quite as loud as the Outlaw and I like the (faux) dual exhaust look.

https://www.holley.com/products/exhaust/exhaust_systems/flowmaster/flowfx/parts/718123

Can I expect a gas mileage increase on this one @Holley Performance Co. ? 🤔
I don't think that they ever suggested that mileage would increase, that's just something I observed and didn't expect.
 

Clearwater native

Badlands
Well-Known Member
First Name
Tom
Joined
Mar 21, 2021
Threads
7
Messages
336
Reaction score
689
Location
Florida
Vehicle(s)
19F-59,16-E350, 65C10,05TJ, 67RSCamaro, 65malibuSS
Your Bronco Model
Badlands
Clubs
 
Installed mine last weekend, it is loud when you take off WOT, the cold start sounds good in the garage, not too bad cruising around easy on the throttle but if you want to sneak away quickly (that isn't happening) I decided to leave the stock brackets on for now in case I decide to switch back, I really think an electric exhaust cut-out like I had on my past Corvettes and Camaro would be nice but for the price you either like it or not.
I am going on a road trip soon and I will find out whether my wife and/or I Decide to like it or not.
 
Last edited:
 


Top