Exhaust Buyer’s Guide
Pulling the long grades of five passes on I-5 in southern Oregon with a trailer in tow always has my grandpa watching the fuel gauge drop in his truck. My dad doesn’t care how much fuel he’s burning but monitors the exhaust gas temperatures (EGT). He just wants to get his truck and trailer over the summit without slowing down. So there are two different reasons I installed aftermarket exhaust systems on their trucks.
Like many of the systems in a truck, the exhaust was designed and built with several compromises in mind. Optimal power output could be achieved with very short and open pipes like you would find at the racetrack. Most people prefer not to breathe exhaust, so it is routed out the back of the vehicle — compromise. Most drivers would rather not have to wear ear protection while they drive and local ordinances regulate noise emissions so mufflers were added (which restrict both air flow as well as sound) — compromise.
As a society, we decided to take measures to cut back on emissions with systems that further restrict airflow. This is yet another compromise in engine efficiency. Vehicle manufacturers have budgets to meet to keep vehicle costs down. This often means cutting corners on exhaust materials and manufacturing processes. You guessed it, more compromise.
It doesn’t take a truck engineer to figure out that these compromises are affecting, to some degree, your vehicle’s ability to pull your trailer. Today’s tow vehicles are marvelously effective and productive when towing trailers that fall within the manufacturers’ towing specifications, but there’s always some room for improvement. Enter a large selection of aftermarket exhaust systems, which address some of the compromises with a decidedly performance-driven bias.
Improvements to engine efficiency by freeing up exhaust flow to increase horsepower and torque are quite useful for towing your trailer.
Because an internal combustion engine is basically an air pump, freeing up the exhaust flow with an aftermarket exhaust system can give engines the opportunity to breathe better, resulting in improved performance. While you can see gains in horsepower, torque and fuel mileage from an exhaust system alone, it really shines in conjunction with other modifications such as an intake, performance chip or reflash that optimize computer-based calibrations.
Not all aftermarket exhaust systems are built the same. In general, you can tell how much of the stock exhaust system each replaces by its name. For example, you can get a turbo-back exhaust system for a turbocharged engine, which replaces everything from the turbocharger back. A cat-back system replaces everything downstream from the catalytic converter.
How much of the exhaust system you choose to replace is an important decision. In general, you can get the best performance improvements by going all the way to the turbocharger or to the cylinders with headers. However, there are some critical components in the OEM exhaust systems of late-model vehicles that put them in compliance with emissions regulations.
A turbo-back system, for example, will replace the stock catalytic converter. If you are concerned with emissions or you live where emission systems are inspected, you may want to look into options that include an aftermarket high-flow catalytic converter or a less inclusive cat-back system.
If you have a newer model diesel pickup, chances are it is equipped with a Diesel Particulate Filter (DPF). There are exhaust systems that delete the DPF. These are often marketed as off-road-only because there can be consequences for removing systems including fines and refusal by dealers to take the truck in on trade. Don’t jump in too lightly to getting rid of a DPF system. Instead, explore the benefits of a DPF-back exhaust system.
Under New Management
For turbocharged vehicles (gas and diesel), the exhaust pipe directly after the turbocharger is commonly referred to as the downpipe. The exhaust that connects the head to the turbo is the exhaust manifold or the turbo manifold, one for each bank of cylinders.
The ideal exhaust for a turbocharged engine is a large, straight-through design with as little back pressure as possible — the turbo itself is enough backpressure for the engine. Since the flow through the exhaust side of a turbocharger is directly proportional to the pressure the compressor side produces, it requires a specific air-fuel ratio to ensure the safety of the engine. The engine management computer must be calibrated to the new exhaust.
If you have a naturally aspirated engine (not a turbocharged variant) then the first piece of the exhaust is commonly referred to as the header. If you don’t want to leave any performance on the table, your exhaust system should include replacing everything from the valves to the tailpipe, which includes the exhaust manifold or headers.
Most exhausts are being built with stainless, aluminized or mild steel with stainless being the most durable. Where you live and environmental corrosion factors are important in choosing what type of material is going to be the best fit for your vehicle. Stainless steel and aluminized steel can better handle winter driving salts, which can rust through exhaust systems quicker when they’re built with mild steel.
If you are paying more for stainless steel, make sure you pay attention to the alloys of the stainless steel. Exhaust manufacturers can explain their choice in stainless grade, which can determine the longevity of the system.
In general, mandrel-bent tubing is preferable to crush bent. Mandrel-bent systems are more precise in meeting the shape requirements and it does a better job of retaining its shape and providing the best flow characteristics.
A local exhaust shop can make a cheap exhaust system using crush-bent tubing but it gives up efficiencies by using the cheaper method of bending the exhaust. Like anything else, quality comes at a price.
Grandpa wants to save on fuel and dad wants to pull the pass with authority. Personally, I like to hear the engine on anything I’m driving and I definitely like the benefits of improved performance. If an aftermarket system comes with a trick looking exhaust tip, that’s an added bonus. Here are some products we found that look and sound great while improving performance, however you define it.
The new ATLAS exhaust from Advanced Flow Engineering is engineered to perform in extreme environments. This system is constructed from mandrel-bent 4-inch aluminized steel tubing for maximum flow, increased horsepower, increased torque and lower EGTs. The two-piece tailpipe and bayonet-style hangers provide a hassle-free installation. To provide a leak-free seal, OE-style band clamps are used that offer a 360-degree sealing area versus cheap U-bolt clamps used in other systems. A 12-inch free-flowing straight-through designed muffler is used to produce a deep, powerful sound. Systems are available in 4-inch turbo back or 4-inch down pipe back with or without a muffler. ATLAS exhaust systems are the perfect combination of performance, fit and value. aFe; 951-493-7100, afepower.com.
The factory driver’s side exhaust manifold on the 2001-2010 6.6-liter Duramax engine in Chevrolet and GMC pickups is pitched down to allow for steering shaft clearance, and as a result, the manifold doesn’t flow as efficiently as it should, according to BD Diesel. The Full Bore exhaust manifold from BD restores exhaust flow balance improving power and reducing EGT. Made from high-silicon ductile iron, the Full Bore is a direct bolt-in replacement for the factory manifold and comes drilled and tapped to accept the most popular EGT probes. BD Diesel Performance; 800-887-5030, www.dieselperformance.com.
Borla headers are designed to improve flow and lower temperatures for increased torque and horsepower gains. See Borla’s website for applications of its custom-designed and tuned exhausts to fit the exact year, make and model of a vehicle for optimized performance. Borla header pipes are built from stainless steel and are made to last. Mandrel-bent tubing maintains pipe diameter through the pipe for maximum flow. All-welded construction and thick flanges ensure strength for a lifetime of reliability. Race, tow or cruise with Borla Headers backed by a 1,000,000-mile warranty. Borla; 800-462-6752, www.borla.com.
Borla cat-back systems are made of stainless steel. Borla employs all-welded construction and mandrel-bent tubing to deliver an exhaust product that according to the manufacturer is easy to install because it fits the vehicle like a glove. Many Borla products also claim to improve gas mileage over stock exhaust. The technology that is incorporated into Borla exhaust systems can provide up to a 5 to 15 percent increase in horsepower and torque depending upon your fuel management system’s ability to provide the right amount of fuel to match the extra airflow. All Borla cat-back systems are backed by its 1,000,000-Mile Warranty. Borla; 800-462-6752, www.borla.com.
dB Performance cat-back exhaust systems are available for Ford, Dodge/Ram and GM pickups, including diesels. They feature a straight-through design to maximize airflow and can help improve fuel efficiency when towing. Manufactured in the USA with stainless steel construction, the exhaust systems deliver the rugged growl that truck owners desire with no annoying in-cabin drone. They feature Slash Cut stainless steel tips that are laser etched with the dB by CORSA logo. All dB Performance Exhaust Systems come with installation hardware, an illustrated installation guide and a 10-year warranty. dB Performance Exhaust; 440-891-0999, www.dbexhaust.com.
DynoMax has launched a performance exhaust system that delivers a throaty exhaust tone and drone-free performance to the popular 2011-12 Ford F-150 5.0-liter truck. Designed to maximize exhaust flow, towing power and minimize fuel use, the new stainless system includes 3-inch mandrel-bent, OE-grade tubing, a 4-inch polished and logo-engraved tip and the exclusive DynoMax VT muffler. The VT muffler is designed around a precisely calibrated patented internal valve, redirecting exhaust flow during cruising conditions to limit unwanted drone. An exclusive Performance and Sound guarantee lets enthusiasts try the system. Consumers can return the product within 90 days for a full refund. The system also is covered by a limited lifetime warranty. DynoMAX; 734-384-7806, www.dynomax.com.
Add some rumble to the 3.5-liter EcoBoost in the 2011-2012 Ford F-150 with Flowmaster’s 409S cat-back exhaust. Backed by a lifetime limited warranty, Flowmaster’s F-150 system features mandrel-bent 16-guage 409S stainless steel tubing and includes 2 1/2-inch piping for either Dual Out Rear or Dual Out Side configurations to fit individual preferences. Force II systems deliver a moderate exterior tone and moderate to mild interior tone making them popular for towing applications where efficiency improvements are desired without a lot of noise. Designed for an easy fit, the cat-back exhaust includes all necessary parts and hardware for a painless installation. Flowmaster; 707-544-4761, www.flowmastermufflers.com.
For owners of Ford’s popular 1999-2003 F-250 and F-350 trucks equipped with the iconic 7.3-liter Power Stroke diesel, Flowmaster offers its bolt-on turbo-back Force II exhaust, part number 817544. Featuring Flowmaster’s patented Laminar Flow Pro Series muffler, this single 4-inch diameter exhaust provides a mild to moderateperformance sound inside and out, while giving the truck the claimed performance and mileage increases. Engineered on the vehicle, the system includes all necessary hangers and hardware, and exits behind the right rear tire with a full 5-inch polished stainless tip. Manufactured in the USA from heavy-gauge 409S Stainless Steel, this exhaust is engineered to last the life of the truck, and Flowmaster’s Lifetime Limited Warranty provides quality assurance. Flowmaster; 707-544-4761, www.flowmastermufflers.com.
The Black Series from MagnaFlow Performance offers the same stainless construction as its other system but with the added protection and style of High Temp Satin Black Ceramic coating applied from tailpipe to tip. The coating has a 1-year warranty, while the rest of the exhaust has a lifetime warranty. MagnaFlow exhausts are dyno tested and proven to make power, with gains in horsepower and torque. MagnaFlow Exhaust systems feature a deep tone and are easy to install. The MagnaFlow Black Series is available for a variety of popular models. See its website for details. Magnaflow; 800-824-8664, www.magnaflow.com.
MBRP produces aftermarket performance exhaust products for diesel and gas powered SUVs and pickups, as well as a broad range of other applications. Within the SUV and pickup category it offers single and dual exhaust kits in three material grades, as well as black coat. MBRP exhaust designed its exhaust to increase the amount of hot dirty exhaust gases removed from the engine, lower operating temperatures and improve engine efficiency. The cost of installing one of its systems can be recovered surprisingly quickly, especially if you install it yourself, something that can be done easily using common hand tools. MBRP; 888-636-7223, www.mbrp.com.