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So, about those exhaust baffles

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Anyone notice a power difference with them out? I have a story to tell, but let me start with the short of it first:

Full removal of baffles caused a reduction in low and mid range torque(!).

My story is like this:

The first Boss I drove was a brand new 2013 straight off the Ford lot. This was when I was shopping around for cars, and the Boss was high on my list.
The car drove wonderfully, and I noticed the meat in the mid range. Fast forward to a week later, I test drove a 2012 Boss with baffles out. The sound was glorious. Intoxicating. Very much a Trans-am sound. However, when I test drove this car, I noticed a lack of power in the middle. I thought it must've been my imagination, since it's been a week since I drove the brand new 2013. Didn't think anything of it and ended up purchasing the 2012.

Only about a week ago, I got plates in the mail thanks to Rick. I ordered some 3/4 baffles.
I put them in only to experiment with the sound. Audibles aside, I noticed a marked increase in mid range torque. The car really moved in a rev band in which it wasn't so response before. Furthermore, my 6th gear was actually useful on the highway--that is, if I'm crusing at 120kph and want to slowly increase speed to make a pass, I can easily do so. Previously, with all baffles out, 6th gear was useless. I would use it to maintain speed, but if I needed to make any changes in velocity, I *had to* downshift--I'm absolutely fine with that, but even if I only wanted to move the needle 10kph, it was painful to do in 6th gear. It was like the car was dragging an anchor.

With the baffles back in (3/4 size), I got my torque back. It totally reminds me of the 2013 I drove back at Ford. The car behaves different--the power curve feels different. It's substantial enough that you can tell by the seat of your pants (no placebo here--as the exhaust volume is decreased...I wasn't even looking for a power difference, but it was very apparent). Power was apparent enough that my passenger noted the same change.

I searched around google for a bit to see if others experienced the same thing, and there are a couple members in the thread below which notes the same observations:
http://www.boss302forum.com/topic/14265-exhaust-with-restrictor-plates-removed/page-2

Just putting this out there. I love the sound of full open side pipes, but absolutely not at the cost of mid range power. So I put the 3/4 back in and I'm happy.
I ended up thinking of it this way:

The side pipes are very much like an exhaust leak. I wonder if the divergence of exhaust gas flow is affecting power delivery. It may affect scavenging, or general velocity of the gas in the pipes. Either way, having a leak upstream of the exhaust is not always ideal. I understand that Ford put the side pipes in there purely for sound (and I admit that I enjoy it very much), but it seems that opening them up excessively definitely costs something.
 
If your 444hp car feels like it is dragging a boat anchor, then something is wrong and its not the exhaust baffles. Are you sure you're not leaving the emergency brake on?
 
I run with the sides wide open, I personally can't tell whether there is more or less when I close them. I do know that it sounds faster at WOT. If I nail it when they are closed the fun factor is still there. I might be splitting hairs but it seems to get up to speed a little better. Try it your Trackey, might help.

BTW: I have the electric cutouts, makes the tuning of the side-pipes easier.
 
Yeah...I'm wondering if there is another issue. The baffles (in or out) should not make a noticeable difference in performance characteristics. Ford designed the car to run with the baffles out. The only reason they are even in is to satisfy the federal sound nannies.
 

MGCurry

2013 Boss 302 #1548 SBY
thew qtp? can you control between WO and Closed can you dial it to 3/4 , 7/8's etc?
racered302 said:
I run with the sides wide open, I personally can't tell whether there is more or less when I close them. I do know that it sounds faster at WOT. If I nail it when they are closed the fun factor is still there. I might be splitting hairs but it seems to get up to speed a little better. Try it your Trackey, might help.

BTW: I have the electric cutouts, makes the tuning of the side-pipes easier.
 

Domestic Product

Big fat tires and everything !
I think you would have to do timed runs with all things equal. Baffles in and baffles out. My bet is the car is faster with them out. I have seen several dynos with the baffles out giving you more HP and TQ not less.
Sixth gear is there for cruising on the interstate and allowing Ford to claim a higher mpg then I'm sure any of us are getting. Also that annoying skip shift thing that everyone should un plug. I never use sixth gear unless I'm on the freeway and not always there either.
I picked up my Boss used and thought wow this thing sounds awesome. Can't wait to get the baffle's out.
Had it in the shop for the usual mods with removing the baffles on the list. Previous owner had already removed them :p
Anyways it's your car and if you like the 3/4" baffles then run them and enjoy the car.
 

Grant 302

basic and well known psychic
I am somewhat skeptical of the results, but not surprised if there is a significant torque loss somewhere under 3k.

There are dyno sheets showing gains of a few HP in the upper RPMs and I think some did show small losses in a spot or two, but not anything that I think could be felt under controlled conditions either way. Though I am certain we can feel the difference that the PCM makes for timing in 68 degree air vs 80 degree air temps. Only a datalog including such parameters would be a valid test.
 

Justin

Save the dawn for your dishes!!!
Domestic Product said:
I think you would have to do timed runs with all things equal. Baffles in and baffles out. My bet is the car is faster with them out. I have seen several dynos with the baffles out giving you more HP and TQ not less.
Sixth gear is there for cruising on the interstate and allowing Ford to claim a higher mpg then I'm sure any of us are getting. Also that annoying skip shift thing that everyone should un plug. I never use sixth gear unless I'm on the freeway and not always there either.
I picked up my Boss used and thought wow this thing sounds awesome. Can't wait to get the baffle's out.
Had it in the shop for the usual mods with removing the baffles on the list. Previous owner had already removed them :p
Anyways it's your car and if you like the 3/4" baffles then run them and enjoy the car.
+1
get it on a dyno run it with them in three pulls then out three pulls. that will settle it. butt dynos are highly inaccurate
 
+2, totally agree. Sound can defiantly un-calibrate the butt-dyno. Though, small differences in the exhaust track can do weird things to low and mid-range torque. Look at the differences in mid-pipes between X-pipes and H-pipes.
 
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Sorry guys,

Just read the thread I posted and noticed that it could have been a bit misleading. One of the guys in there theorized that the power loss was due to a reduction in back pressure--I am in no way saying this is the case, and that makes very little sense to me :)

All I'm saying is it was an interesting finding for me--even when I wasn't even looking for a power difference--I just felt it.
Could it be because the exhaust is "leaking" out the side, rather than being funneled through the length of tubing and accellerated out the mufflers? I don't know.
But we can look at it this way: Having the side exhaust is like having 2 small holes drilled on either side of a gun barrel. The purpose of barrel length is to accelerate the projectile so that there is greater accuracy and muzzle velocity. I could see how having 2 small holes on either side deminish the muzzle velocity.... Note that I'm talking 2 holes somewhere in the middle of the barrel--not near the end. Our car's exhaust is the same way. Could be something there.

I'm not debating that there is greater top end with the baffles out (esp if it's dyno tuned), but I really do notice a low to mid range difference out on the street. Car is much more meaty in those rev bands. Just my observations... FWIW.
 
The rumor is the 3/4" discs add 10 HP. But don't everyone order a set at once or I'll run out. ;D

Removing the discs with the stock mufflers is supposed to add a couple of HP at most. Not sure if the torque drops.
 
MGCurry said:
thew qtp? can you control between WO and Closed can you dial it to 3/4 , 7/8's etc?

If you have the wireless remote you can stand out side of the car and adjust it at idle or have someone regulate the gas for ya.
 

Grant 302

basic and well known psychic
http://www.mustang50magazine.com/techarticles/m5lp_1208_boss_302_exhaust_sides_and_sounds/viewall.html

This isn't on a Boss, but some interesting results on a GT with the Boss exhaust with and without discs. With the Boss exhaust and stock discs, there are only gains. Without the discs there are a few spots with small losses from stock and with discs.

Too bad data is only from 4k up.
 
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Grant 302 said:
http://www.mustang50magazine.com/techarticles/m5lp_1208_boss_302_exhaust_sides_and_sounds/viewall.html

This isn't on a Boss, but some interesting results on a GT with the Boss exhaust with and without discs. With the Boss exhaust and stock discs, there are only gains. Without the discs there are a few spots with small losses from stock and with discs.

Too bad data is only from 4k up.

Yup. Looking at that, it shows only gains from 5200rpm and upwards without the baffles. Anything under that rpm, the baffles yield more hp and torque.
They're not large (looking at the numbers)...but my car will see more street than track time, so I care about what's under 5200 also :)

And admittedly, I'll add what is my own speculation here:
The GT intake manifold peaks hp and torque at much lower RPM's. With the curve moved significantly to the right with our Boss manifolds, we're may see a greater torque/hp loss with the baffles out. Whatever the case, it's something I noticed immediately even when I wasn't looking for any power change. In my case, I chose low to mid range power over the awesome sound of a baffle-free exhaust. So I stuck with the 3/4 size.

I wonder, has anyone tried going back from full open to a stock (or smaller size) and noticed any difference as well? I know I'm not crazy, as others have noticed it on various other forums as well.

Note: I fully understand that an upgraded exhaust will yield gains. IMO, the Boss's quad exhaust is not a true exhaust upgrade. It's done to add to the driving pleasure--and that is to add some unique aural attributes to the character of the car.
 

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