How To

Make Your 2005-2009 Mustang V6 Growl

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by Huw Evans  More from Author

Exhaust Upgrade Gives Throaty Tones and Better Throttle Performance

There’s no question, that the 2005-2009 Mustang (chassis code S197) represents tremendous value. With an entry-level manufacturer’s suggested retail price of $20,430 (brand new) in 2009, and now good used examples trading hands for $15,000 or less, there are few cars today that can match the S197 V6 for performance, style, and especially charisma. Since the car was launched, the V8 powered GT model has received the lion’s share of attention when it comes to publicity and performance upgrades, but the V6 cars outsold it by a 2-1 margin. And, in these times of economic sobriety, the base Mustang makes a lot of sense, it’s better on fuel, cheaper to buy, and cheaper to ensure, but just as fun.

One drawback concerns the factory exhaust. Routed after the manifolds into a single system, culminating in just a solitary tailpipe on the right side of the bumper, it hardly seems in keeping with the sexy looks of a ponycar. The sound is also best described as something like a muted chainsaw, not helped by the 4.0-liter V6 engine’s firing order.

There’s a cure for this problem – install a throaty, converter back, dual-exhaust system. There are a couple of ways you can do this. The cheapest way is by getting your hands on a used 2005-2009 Mustang GT exhaust system, the mid-pipes, mufflers and tips. They are literally a dime a dozen and can be purchased for anything between $0 and $60 since most GT owners take them off within weeks of buying their cars and they’d otherwise be going in the dumpster. The only thing is, to install this system, you’ll need to fabricate a Y-pipe collector to mate the dual pipes with the V6 Mustang’s single tube that runs from the converter back.

The second route, is to pay for an aftermarket replacement dual exhaust system designed specifically for 2005-2009 V6 Mustangs. A number of companies sell them and two of the most popular on the market are those from Magnaflow and MAC Products. The complete MAC converter back system is designed to fit 2005-2006 Mustangs with the 4.0-liter engine (P/N TK2625). It features dual replacement mufflers with a pair of big four-inch tips, made from 304, aircraft grade stainless steel, dual 2½ inch stainless steel pipes, a stainless Y-pipe with single in and dual out collectors, plus brackets for the mid-pipe and muffler sections and replacement screws. At the time of this article it retailed for $499.50. MAC also sells other specific V6 S197 exhaust pieces, including headers, and off-road systems, but in the interest of staying street legal, we opted to stick with a pure bolt-on converter back, replacement exhaust. So now we’ve got the kit and a car to install it on, let’s get started.

Our subject vehicle is a black, 2005 Mustang V6 coupe. Recently purchased used, it’s a low-mileage example and 100 percent bone stock. The single exhaust system is fine from the factory, but the car’s new owner wants a bit more personalization as well as an exhaust note more befitting of a sporty ride.

Here is our new system in all its glory. Isn’t she a beauty? Although, due to the efficient nature of the 4.0’s factory exhaust system, aftermarket gains in horsepower and torque are minimal, for looks and sound, the MAC system is hard to beat. The dual four-inch tips and full stainless steel construction really take it to the next level. The system requires no welding for installation (as you’ll see) and MAC offers a 50,000 mile limited warranty on its 2005-2006 V6 kit.

Before we can start installing the new parts, the old, factory spec single exhaust system needs to come off. Here Da Silva Racing technician Rob Coehelo gets to work, removing the car’s 2¼-inch mid pipe behind the catalytic converter, using a saw.

Once the mid-pipe section is removed we can then tackle the muffler and tip. Be careful when removing it from the hanger. MAC does not supply new hangers, so you’ll need to make sure your existing one remains intact (but more on that later).

Something that we’ve noticed on quite a few aftermarket exhaust kits is the size of the exhaust clamps. On the MAC kit, the clamps designed to fit on the rear section, in front of the mufflers are very small (compare them to the supplied clamps for the forward section – right). In an effort to keep rattling and vibration to minimum as well as promoting long-term durability, we won’t be using them.

So, with the original muffler off the car, Rob removes the original factory muffler clamp, using a hammer to pry it off the tube. We’ve got several more available in our spares box, but if you need replacement clamps to do this installation, get your hands on some factory 2005-2006 Mustang GT muffler clamps, easily available at your local salvage yard or parts store.

Now, because V6 Mustangs only come from the factory with a single exhaust outlet, and our replacement system has two of them, we need to create a mount for the left side muffler and tip. The first step is to drill a hole in the framerail on the driver’s side so we can install a second hanger. You’ll need to measure the distance from the hole to the rear bumper cover on the passenger side, as well as the diameter of the hole, in order to do this correctly on the driver’s side.

One thing we should stress if you’re planning on installing this kit, is to make sure that, besides new clamps, you get your hands on a left side exhaust hanger from a 2005-2006 Mustang GT. They are not hard to find, and should not cost you more than a few dollars. Again, your local salvage yard is a good place to start. Here, with our hole drilled on the left side framerail, you can see the new hanger installed.

Something else we need to think about before installing our new exhaust system is the rear bumper cover, because at present, there is only a single exhaust cutout on the right side. There are a couple of options you can take. The most expensive is to remove the original V6 bumper cover and replace it with a GT unit that features dual cutouts. If you choose this option, the front and rear fascias don’t match and the car looks awkward. The second option is to make a hole in the existing rear cover, which is much cheaper and if done right, will look factory – the route we decided to take. Here we take a piece of tracing paper and mark out the cutout on the passenger side, so we can make a template for cutting out a hole on the driver’s side.

With the area needing removal now marked on our sheet of paper, we carefully cut it out. Make sure you take your time doing this.

Now, we take what’s left of our piece of paper, reverse it and carefully tape it to the bumper cover on the driver’s side. Make sure that you measure the distance from the edge of the bumper cover to the hole on the passenger side, and duplicate this for the driver’s side. Otherwise, the cutouts won’t be symmetrical and your new exhaust won’t look right.

The next step is to carefully remove the unwanted material. The best way to do this is by using a small air saw. You’ll need patience and a steady hand to do this correctly.

Once the excess material was successfully removed, we used a Dremel tool, to carefully remove any sharp edges from our new exhaust cutout on the driver’s side. Once that was done, we used a file to further smooth any remaining sharp pieces.

Now it’s time to start installing our new exhaust system. The first thing is to test-fit the parts for clearance and proper fit. The best place to start is with the mufflers.

Once that was done, we could turn our attention to the mid pipes. Often, when purchasing an exhaust kit like this one, you should inspect the ends of the pipes as sometimes they can get crimped or squashed during shipping. To make sure each section of the exhaust could mate properly, we used a pipe-expanding tool, to ensure the diameters on each section correctly matched.

With that done, we could now start fitting the mid-pipe and Y-pipe sections to the car, along with our new, replacement clamps. This can be an awkward job so make sure you’ve got two pairs of hands, as some adjustment and alignment will be needed.

Even with the Y-pipe section in place on the car, you might need to use the pipe-extender again to make sure each section properly connects, we did in our case.

We also found that our mid-pipes were a bit too long, so we used a rotary saw and grinder to remove approximately two-thirds of an inch where they mate with the Y-pipe collector. In our case, that fixed the problem.

At the back, you might find that muffler alignment is off slightly and you’ll want to adjust each side to make sure they look as symmetrical as possible. Using an extra pair of hands and a crowbar is often the best way to do this.

After making sure the entire exhaust system fits properly from the converter back to the mufflers, we can now torque the fasteners

With one more final inspection, our dual exhaust conversion is now complete. Doesn’t it look fantastic? We think so.

Now that everything looks good and we’re happy with the installation, it’s time to go for a test drive to make sure there are no rattles or excessive vibrations in the system.

In our case, everything proved fine – the exhaust note was much more authoritative without being intrusive, throttle response was actually a bit better, and to top it off, the dual system looked like it was installed at the factory. Time to hit the road.

Da Silva Racing
(416) 847-1500

MAC Products Inc.
(800) 367-4468


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