Do muffs help flow?

Can a 2" diameter ball roll faster through a 6" pipe than a 4" pipe? Increasing flow capacity beyoond what’s necessary for unrestricted passage of the gasses holds no benefit whatsoever. We don’t have any details on the vehicle whatsoever, but I seriously doubt of the new muffs made any difference whatsoever. The exhaust systems on modern cars are pretty well optimized in order to meet CAFE goals while still keeping emissions down.

I could “feel” my '72 Vega handle better on the highway when I put the plastic spoilers on it too. It’s normal, even healthy, to “feel” a difference. Actual testing usually discloses these improvements to be pretty much just the normal enjoyment of having made an “improvement”.

Back when I had my 95 Bronco (351W), I had a custom exhaust put on, shorty headers, dual exhaust (no cats, no mufflers) that culminated in 4 inch tips. There was a noticeable difference. It should be noted that a pair of GT-40 heads were swapped in at the same time (which necessitated the need for the headers, as the stock manifolds would match up with the GT-40’s exhaust ports.) So it’s possible that the new heads helped out a bit as well. With that said the stock exhaust systems on the pre 97 Ford trucks are basically a one size fits all affair, not matter what engine your truck had, the exhaust system was basically the same, the big bottleneck on those trucks in the dinky stock pipe that connects the stock exhaust manifolds to the rest of the exhaust system. The 79-93 V8 Mustangs also had a pretty restrictive stock exhaust system.

I think opening up the exhaust some on some of the older carbureted cars could help a bit; mainly with the single as compared to dual exhaust systems.

While poring through a very old service manual once I got to comparing horsepower and torque numbers on some of the old sleds and the specs show a difference.
WaY back when, a dual exhaust was often an option and the Buicks, Olds, Pontiacs, Cadillacs, a roughly 10 to 20 horspower gain on the cars which were equipped with the dual exhaust option.

I also reading once where Motor Trend, Car and Driver, or whomever, was testing a new at the time 1969 Dodge Superbee and it was faster than expected. It was discovered later on that Dodge had tweaked the car a bit before handing it over for testing and it was not stock. One of the tweaks, other than a dual point distributor, was increasing the size of the dual exhaust pipes by 1/4".
That extra quarter of an inch along with the other tweaks was not very noticeable so Chrysler got some favorable press by fudging a bit.

I suppose @Stoveguyy you could do a little experiment – this might not be entirely legal if you actually drive the car on the public street this way, and it might damage the cat , and you might get asphixiated by carbon monoxide — but in theory at least you could completely remove the muffler and do a short test drive and see if you notice any performance improvement. If not, then you’d know at least that muffler changes won’t help performance in your case.

Ok4450, I agree with you. I don;t think a lot of engineering went into those old systems.
But I like to think today’s systems have far more engineering behind them. Perhaps I’m giving the manufacturers too much credit.

I’m pretty sure that if you take any car and remove its exhaust system, you’ll notice a difference in how it runs, and probably not for the better since the intake will be sucking in exhaust.

@FoDaddy, if I had to bet what made the difference on your Bronco, I’d bet on the catalytic converter(s) being removed probably made the largest difference. That being said, my conscience would never let me do that. If I could find a way, I’d install a catalytic converter on a motorcycle.

I do bang for the buck,anything that gives a small increase at 5500-6000 rpms,will not help me one Iota-Kevin


Where I live they don’t do emissions testing, the only thing they really care about is if the exhaust pipe exits behind the passenger compartment of the vehicle, though side pipes are allowed.

The only way to know about any performance enhancing product is to do a dyno run before installation and a dyno run after. If the lines are the same for torque and HP then no change. If lines are different there could be improved or reduced torque and HP. Folks feel the difference because they spent a bunch of money and hope it did something.

Often the new gizmo’s in fact decrease performance. Aftermarket “turbo” mufflers are likely louder and that might be perceived as more power, but actual changes in performance is doubtful. Before the exhaust ever gets to the muffler it has to pass through the cat and sometimes resonator (small mufflers) and finally reach the main muffler(s). The stock systems are carefully designed and hard to improve upon. In the 50’s, '60’s and '70’s less restrictive mufflers made a big difference especially when you put on a larger carb and less restrictive intake manifold.

In this Caddy, no significant difference except a lighter wallet.