Somewhere it's an unwritten rule that if you have a rear-drive V8 American car, it must have dual exhaust. That's just the way it is. So if you've got a 5.0 engine in your Cat, no matter what year, you're probably thinking about putting a dual exhaust setup on the car. Considering that our car is generally a big Mustang, it would make sense that a Mustang-type dual exhaust will fit on the Cougar, right? Well, yes; in fact, you can use the entire system on the Cat with a few minor tweaks here and there. Rest assured, no matter what anyone else tells you, you WILL be able to put dual exhaust on your Cougar.

But where to start? Should you go with a stock Mustang system? Or what about the off-road and high-flow H-pipes? Or the newer X-pipes? Or should you just have a custom system bent for the car? These are some serious questions that you have to figure out on your end. Once you do, read on below to see what you're getting into first. Whether you're on a budget, or want the absolute best, or want to strike a happy medium, there's a section below that will fill your needs.

Before you haul off to buy parts, there are a few things you need to understand about your car first:

TRANSMISSION CROSSMEMBER
A lot of Cougars and Thunderbirds from 1983-88 have the "double-hump" transmission crossmember from the factory. So if you have one, there's one thing you don't have to worry about...otherwise you'll have to hunt one down. This crossmember is so named because it has the two humps necessary to clear a dual exhaust system. Some cars only had the single crossmember, meaning it won't work with duals. You can find one from any 5.0 Mustang from 1986-93.

FUEL FILTER
Since no 1983-86 car ever left the factory with duals, there are a few anomalies with putting duals on that body style. The fuel filter (and sometimes a second fuel pump) is located on the rear frame rail, passenger side, right in front of the rear axle. Guess what? This is the spot where the passenger muffler goes. So you'll need to a) reroute the filter and/or pump, b) run a skinny muffler, such as a Cherry Bomb, or c) live with the passenger muffler hanging down lower than the driver's side. You will need to crawl under your car and determine the best course of action.

Also, there are no hangers for the muffler or the tailpipe on the passenger side. You can use stock Mustang or 1988 V8 Cougar/Thunderbird hangers, if you wish. Problem is, if your new exhaust kit comes with the hangers pre-welded onto the tailpipes, the hanger will hit the fuel filler neck on the passenger side. Not a good thing; in fact, it's extremely dangerous. This will necessitate having the tailpipes lengthened to clear the filler neck. But then where do you hang them? We've used universal hangers with fair success. With a little creativity you can come up with something. Now for the 1987-88 Cougars, Ford did some rerouting of the brake and fuel lines so putting in duals is a snap. If you've got an '88 with the factory duals, and are ditching the split Y-pipe for an H- or X-pipe, you're in excellent shape.

EXHAUST MANIFOLDS
All V8 Cougars have factory cast iron exhaust manifolds. A stock or aftermarket H- or X-pipe will not bolt up to the factory cast iron manifolds without fitting and leaking problems. So when you're planning your dual setup, you must take this into consideration. The most popular option to get around this is using the lightweight factory headers from a 1986-1995 Mustang 5.0 motor. Honestly, most Mustang guys would be just as happy to throw them away. Therefore you can probably pick up a set for next to nothing. Or you can go with aftermarket headers, pocketbook permitting. If you've got the stock 140-150hp motor, or have converted to HO and are running the stock HO setup, and you will not be doing any other motor work, you should run 1-1/2" unequal length headers. Anything over 225hp, or using radically-worked heads, should use 1-5/8" unequal length headers. If you put 1-5/8" headers on a 150hp motor, you're really going to bog down big time. That's simply too much header for the power output. Also, equal-length headers (the ones that look like a bunch of twisted tubes) can be used for higher-horsepower engines, although getting them to fit is sometimes difficult. One other thing to note about all headers: they are tuned, so any header will give you a great sound from the motor. Most people assume that changing mufflers is what alters the sound; while partially true, the real key is in changing from cast iron manifolds to headers. One final note about the factory exhaust manifolds: if you're getting a custom-made dual exhaust system, the mechanic should easily be able to make the pipes fit up to them. If it can be done for a V6, then it surely can be done for a V8.

COLUMN SHIFTER
Another annoyance has to do with your gear shifter. Most Cougars came with the column shifter from the factory, and only XR7's and optioned-out cars got the cool floor shifter. The column shifter uses a whole bunch of rods and linkage right around the driver's side exhaust manifold to connect to the transmission. For this reason, no matter what transmission you've got (AOD, C3, C5), your linkage will present a problem with the exhaust system on the driver's side. Using the stock Mustang headers is a great choice here because they usually clear everything just fine. But you will definitely have to watch with the O2 sensors (see below). For an AOD with the column shifter, you can usually get the O2 sensor to fit between the linkage with no clearance problems. You may end up rearranging some linkage a bit, but it will work. Other transmissions may also have a similar solution. Best thing to do is measure everything and make sure you'll be okay; better yet, see if you can get the car up on a lift and check that way.

FLOOR SHIFTER
Now with the floor shifter, there's another unique problem. The bracket that holds the kickdown cable (aka TV/throttle valve) on the transmission hangs down just enough to interfere with the H-pipe. You will need to grind down the bracket approximately 1/2" to get the H-pipe to fit right. There is nothing more annoying than having the H-pipe squeak every time you hit a bump! For all transmissions alike, please be aware that the factory H-pipe with 4 catalytic converters comes really close to the kickdown linkage on the driver's side of the transmission. If you're not careful with clearances in this area, your kickdown cable can get stuck on the top of the converter and you'll experience some nasty shifting. This is not a safe situation. Our advice: remove the heat shield surrounding that particular converter (the smaller one, toward the front) before you install it. That should assure you of no clearance problems in that area and it won't affect the performance of the converter.

OXYGEN SENSOR(S)
When replacing the exhaust manifolds, you are also removing the oxygen sensors (aka EGO, HEGO, O2 sensors). For any computer-controlled engine, especially with Ford's EEC-IV system, you CANNOT run the vehicle without O2 sensors in place, or else your fuel economy and performance will suffer greatly. You can also cause severe engine damage eventually. So please, do not even think about letting them hang or disconnecting them. So what to do? Well, MAC makes aftermarket headers for 1994-95 5.0 Mustangs that have O2 sensor provisions. That would be the most practical solution. But most of the time they go in the H- or X-pipe, downstream from the motor a bit. All aftermarket and factory H-pipes have provisions for O2 sensors, essentially a bung with a 15mm thread. You can either lengthen the wires on your exisiting O2 sensors (if they're newer), or you can get the O2 sensor wiring harness from a Mustang that will bring the wires down closer to the H-pipe. That's a nice little salvage yard piece, or it can be bought new from IST. If you need new sensors anyway, Bosch sells new sensors with varying lengths of wiring, so you can probably just use those and keep your stock O2 sensor harness. Now you will have to watch the connectors on the O2 sensors, as there are different types. Best thing to do is take your old ones to the parts store and compare the ends with the new ones. If you are putting your own O2 sensor bungs in a new pipe, you will need to place them on the bottom side, before the crosspipe (the "H").

EMISSIONS LAWS
Depending upon where you live, there can be some rather strict laws against modifying your exhaust system. Emissions being what they are today, we would strongly suggest that you contact someone in your state's BMV about your proposed plans to change the exhaust. Some states, such as California, allow nothing over and above what came with the car for that model year. So please keep this in mind. Any item that says "49-State Legal" or "50-State Legal" is what you're looking for, because that means it passed stringent government testing.

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Listed below are some of the more popular choices for putting dual exhaust on a 5.0 Cougar.

H-PIPE
This is what makes true dual exhaust dual, and what most people think of when you picture a Mustang-style dual exhaust. For a used H-pipe, try to find one that has had all 4 of its catalytic convertors replaced under factory recall. As you may guess, it's very expensive to replace all the cats. For a new H-pipe, aim for a high-flow 2 1/2" setup, or an off-road H-pipe----if, of course, your Cougar likes to, uh.....go off road (ahem). Make sure it's 2 1/2", because they usually don't cost much more than the stock 2 1/4" diameter, and you'll pick up a few more horses too. The flanges on the top end (that bolt onto the headers) are difficult to work with because they can only go one way. Plus they like to spin around a lot. By the way, the hooks on top of the H-pipe are for hanging the pipe onto the transmission mount bracket---make sure you do this! You might want to pick up the double-type mount from a Mustang and put that on; however, your stock single-type will work adequately if you can't find a double mount.

X-PIPE
The X-pipe is a relatively new idea for passenger cars. Long used by NASCAR, it equalizes the pulses from the motor better than an H-pipe. This results in a significant horsepower increase (usually between 10-20 or more for just the X-pipe alone), as well as a very strong and very different exhaust note. You can get an X-pipe with high-flow converters or without any converters at all. Currently the front-runners for making the X-pipe are BBK, Bassani and Dr. Gas. Bassani claims that their X-pipe can only be used with either stock or their own headers, although it would probably be best to contact them first and see whether that's true or just a marketing ploy. If you need low-end torque, the X-pipe would probably not be a wise choice. Still, if you want something different, the X-pipe is for you.

CAT-BACK SYSTEM
When purchasing your cat-back Mustang exhaust system, you're confronted by a few choices, and most of the time it usually revolves around how much you have to spend. For all practical purposes it is not wise to reuse an old Mustang exhaust, no matter how tempting. You're much better off in the long run with a new system. Besides, there's nothing like putting on brand new parts. So at the very least, you should purchase an aluminized system. These are the cheaper of the two kinds of kits, and provided you don't bang up the pipes too bad, they're good for roughly 7-10 years of rust-corrosion resistance. Not a bad investment at all. Some of the more popular brands are Flowmaster, Dynomax/Walker, and Thrush. Each kit will fit very differently, but all do pretty much the same job.

On the other end of the spectrum, there is the stainless steel exhaust kit. The most widely known stainless kit is made by Borla, although there are a few others coming into the picture now. Now these kits are really wicked and install like a dream, but they're frightfully expensive, and usually out of the reach of most people. However, the trade-off is that they will never rust. It's quite literally the last exhaust system you'll ever buy for the car.

It is YOUR decision as to which kind of kit to purchase. Our only aim here is to help you prepare for the installation of any exhaust kit, regardless of the metal type. Just remember, you definitely pay for quality with exhaust kits. Oh yes, don't forget to order your kit for a 1987-93 Mustang. If you want turn down tips to clear a ground effects kit, get the kit made for a GT. If you want straight pipes out the back, or wish to add your own exhaust tips, order the kit for an LX.

Also, you can't forget about tube width. Most places will stock 2-1/4" pipe, and should have 2-1/2" pipe, the two sizes that are the most popular for a Ford 5.0 motor. But width will depend on your power output---bigger is not necessarily better. If you've got a stock 140-150hp 5.0, then you'll want to go with the 2-1/4" pipe. The advantage over 2-1/2" pipe is that it fits much better, so less chance of rattling around. Anywhere from 200hp and up, the 2-1/2" system is best for optimum flow. Ultimately, you must decide for yourself what is the best and most cost-effective for you, and make the best decision you can from there.

Now since our cars have quite a bit more body after the rear axle than a Mustang, the tailpipes may need to be lengthened a bit around the fuel tank. This depends upon if you really want them to look good or not. If you're not really concerned about the looks, then a shorter tailpipe won't hurt you a bit. The LX tailpipes are generally longer than the GT pipes.

CUSTOM SYSTEM
Back a few years ago, the only option that a Cougar owner had for putting a dual exhaust setup on his or her Cat was to have a custom-made system. Well, you could put the 1988 "fake" dual kit on, but that won't yield you much. So does this philosophy hold up today, in the 21st century? Well, sure, why not? We've had several people report that their custom systems cost less than the cheapest aftermarket kit. That's a significant savings! But in order to find out if this is cost-effective for you, you will have to do a little research in your area. Mainly you'll have to call or visit muffler shops and find out if they can do this for you, and also to get some pricing. Then simply weigh them all against each other. But first you must arm yourself with some understanding and knowledge of what you're about to get into.

Exhaust systems can be made from 3 different types of steel: regular, aluminized, or stainless. All 3 types will carry a different price, and you have to know this going in. Regular steel exhaust systems are very cheap, but they will also need replaced every 2-3 years. Not just the mufflers---the entire thing. This is not usually the most cost-effective way to go, although the price factor could be tempting. Now an aluminized system takes the same gauge steel tubing and adds an aluminized coating to it. This greatly enhances the metal's rust-preventive properties. In fact, the average aluminized system lasts for 7 years! And the plus side is, it's not much more than plain steel. If you are going through the trouble to put a custom exhaust on your Cougar, please do not consider using anything less than aluminized tubing, or else you will simply be throwing your money away. Now this usually does not include aluminized mufflers---they'll still have to be replaced every few years, more than likely, unless specified by the manufacturer. Since exhaust systems rust from the inside out, it's almost impossible to offer a warranty on aluminized mufflers. The third type of exhaust system uses stainless steel. This is the same type of steel used on your silverware, and it's known for its excellent rust-fighting properties. Stainless exhaust systems are the cream of the crop for this fact. And that also means it's the most expensive. Stainless pipe is much thicker, requires special cutting tools, and must be bent while packed with sand or similar substance. You can see now why it costs so much. But the tradeoff is that this will literally be the last exhaust system you'll ever buy for your Cougar (barring accidents, of course). You will never have to worry about rust eating through the pipes. You will never have to worry about replacing stainless hangers (if they are used). And the finish usually stays shiny and metal-looking for years. This is THE best you can get. So the type of steel used in your custom exhaust system will have a big impact on your wallet.

Before you go taking in your parts that you just bought to the local muffler shop, please check first and make sure that they will install your parts. Some places don't like when you do that to them. If you're allowed to bring in your own parts, and they'll hang them for you, then you may want to look for some mufflers. Not just for performance, but for sound. Let's be honest, the sound factor is half the reason why you're putting duals on in the first place. (The other half is seeing that other pipe hang out the passenger side). So you may as well go for some great sounding mufflers. The major exhaust companies (Borla, Flowmaster, Walker/Dynomax, etc.) do indeed sell their mufflers separately. If you've never heard any of them, talk to a few Mustang guys or hot-rodders. They can give you great input on which ones to get, according to sound. Where do you buy these parts? Best place to look is a high-performance parts catalog, such as those by Summit Racing or Jeg's.

MISC. PARTS & INFO
In moving the fuel filter on 1983-86 cars, it is perfectly fine to simply move it up toward the front of the car, about 6"-8". This will allow clearance for the passenger side muffler. While the muffler is still a really tight fit, it helps out very much indeed. Or, you can relocate the fuel filter outside the subframe rail with relative ease--there's usually enough slack in the fuel line there to do it. Owners of 1987-88 cars should already have their fuel filters in that location. Some cars, like the 1983-85 V6's, have a combination fuel pump and filter. This SHOULD NOT be moved. You will either have to run a very skinny muffler (such as a Cherry Bomb) or dump the exhaust in front of the rear tires.

There is an air tube on the H-pipe that you can't forget about. It's hooked into the Thermactor air system on the car. The air pump (driven off the car's fan belt) feeds fresh air to the heads and the exhaust. This H-pipe air tube is where the fresh air comes in; its basic function is to allow the catalytic converters to receive oxygen so they can catalyze better. The air tube runs between the H-pipe and the junction under the hood, on the passenger side, right next to the header in the rear of the compartment. If your air tube is broken or missing, it is acceptable to run a high-heat hose between the H-pipe and the junction, provided you clamp the hose down accordingly.

I'd also recommend using the new-style band clamps for the entire exhaust system instead of traditional clamps, if possible. They look awesome, provide a 360 degree seal, and are stainless steel for long life. If your exhaust system is stainless, or you're looking for a leak-free and permanent system, then have all the joints and seams welded.

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