Exhaust upgrades are usually one of the first things Mustang owners do. They are often fairly simple to install, not very expensive, and are manufactured by many different companies. We've done exhaust upgrades and tests on stock Stangs showing how much power you can make with just a few hours of work. This time, we've done things a little different.
We all know that the right set of headers will increase power, and they add a roar to the exhaust that most of us crave. The big question is whether to go with short-tube headers or the more racy, long-tube headers. Short-tube headers are often less expensive and easier to install, but you could be leaving some power on the table. So for this exhaust go-around, we've decided to test stock headers and a mid-pipe versus those common aftermarket pieces, and our test subject is an '05 GT five-speed-supercharged by a Magnacharger pumping out 8 psi. Can minor changes like headers and a mid-pipe make a noticeable improvement on such a vehicle? That is what we intend to find out.
We cruised over to the brand-new Brothers Performance supercenter in Deltona, Florida, to perform our tests. Brothers' East Coast facility is not only the distribution hub for all of its East Coast customers, but the 64,000-square-foot facility also features a retail showroom and a shop for installs, tuning, and dyno testing.
Other than the supercharger, our test GT had a Magnaflow after-cat system and was tuned with an SCT X3 tuner. With the help of Brothers Performance's Matthew Grieves, we strapped the Ford to the Dynojet and got busy. Baseline runs yielded 389 rwhp and 366 lb-ft of torque. The next step was to choose which headers and mid-pipe to use. Since BBK Performance is a leader in Mustang performance and Brothers carries the full line of BBK products, we swiped a few combinations off the shelf and started disassembling our test subject.
We started with the BBK chrome short-tube headers (PN BBK 1612), the least expensive ($299.99) and most popular of BBK's short-tube line. Ceramic coated (PN BBK 16120) and stainless steel (PN BBK 16125) are also available. With the shorties in place, we reinstalled the stock mid-pipe and made another dyno run. This yielded gains of 3 hp and 3 lb-ft at the peaks, bringing our totals to 392 rwhp and 369 rwtq at 6,250 rpm, however, this did not tell the entire story. That's because there were much bigger gains under the peak. For instance, at 4,400 rpm the engine picked up over 10 hp. This trend continued throughout our entire test.
With the shorties still in place, Grieves dropped the stock mid-pipe for BBK's X-style mid-pipe with cats (PN 1770). It works with stock exhaust manifolds or BBK's shorty headers. With the O2 sensors plugged in and fittings tight, it was back to the Dynojet for another run.
The '05 GT we used for our...
The '05 GT we used for our test was equipped with a Magnacharger (pumping out 8 psi) and a pair of Magnaflow mufflers.
Not surprisingly, the peak gain was only 1 hp and 1 lb-ft of torque. But, like the previous run, gains were as high as 10 hp and 15 lb-ft of torque over the rest of the graph. More impressive was how much smoother and consistent the graph was throughout the run. Also, this combination caused a spike in horsepower at our cutoff of 6,250 rpm. A small hike in the maximum rpm may have produced greater horsepower at the peak, but the car owner didn't want to turn up the rpm.
Last on our list was BBK long-tube headers and matching X-style mid-pipe. Since this combination was going to be last, and permanent, we opted for the BBK stainless steel long-tube headers (PN BBK 16415) to couple with the X-style mid-pipe with cats (PN BBK 1637).
With the battery disconnected...
With the battery disconnected and the GT in the air, Matthew Grieves of Brothers Performance removed the stock mid-pipe to access the exhaust manifolds. Two of the O2 sensors must be unplugged as the mid-pipe is lowered.
After the starter is removed,...
After the starter is removed, the engine must be supported and the right engine mount removed to access the right exhaust manifold.
The BBK chrome short-tube...
The BBK chrome short-tube chrome headers (PN BBK 1612) are clearly less restrictive than the stock piece.
The stock manifolds are mounted...
The stock manifolds are mounted using studs and nuts. The studs must be removed and the new headers are bolted on with included header bolts.
The BBK mid-pipe for stock...
The BBK mid-pipe for stock or shorties (PN BBK 1770) is equipped with O2 sensor bungs and mounting hardware. Here, Grieves installed the O2 sensors into the mid-pipe.
One person can install the...
One person can install the mid-pipe. The three-piece design allows the installer to bolt the down tubes to the flange, then attach the lower pipe to the tubes.
Not surprisingly, the peak gain was only 1 hp and 1 lb-ft of torque. But, like the previous run, gains were as high as 10 hp and 15 lb-ft of torque over the rest of the graph. More impressive was how much smoother and consistent the graph was throughout the run. Also, this combination caused a spike in horsepower at our cutoff of 6,250 rpm. A small hike in the maximum rpm may have produced greater horsepower at the peak, but the car owner didn't want to turn up the rpm.
Last on our list was BBK long-tube headers and matching X-style mid-pipe. Since this combination was going to be last, and permanent, we opted for the BBK stainless steel long-tube headers (PN BBK 16415) to couple with the X-style mid-pipe with cats (PN BBK 1637).
The long-tube headers, like the shorties, are also available in chrome (PN BBK 1641) and ceramic coated (PN BBK 16410). With the long-tube headers and mid-pipe in place, Grieves strapped our GT down for one last spin of the rollers. True to form, the long-tube combination yielded yet another 4 rwhp and 8 rwtq, bringing our running totals to 397 rwhp and 378 lb-ft of torque. More noticeable, though, was the big increase in torque from 3,650 to 5,500 rpm.
Clearly we made the most power with the long-tube headers and matching mid-pipe. However, this is not a perfect world. As the graph shows, low-end torque was reduced slightly. It was recovered higher in the rpm range, but it must still be noted.
The final results against the baseline test show a maximum increase of 9 rwhp and 12 lb-ft of torque at the peak, but none of us drive at a constant rpm, and certainly not at the redline, so overall power is what you must look at. What we liked most was the significant gain in torque from 3,300 rpm and up. At 4,200 rpm, the gain was over 25 lb-ft-and that equates to better throttle response and a noticeable seat-of-the-pants feel, even on a near-400-rwhp supercharged steed.
With the BBK shorties and...
With the BBK shorties and mid-pipe in place, a quick run on the Brothers Performance Dynojet yielded 4 rwhp and 4 lb-ft of torque over the stock exhaust manifolds and mid-pipe.
Next up were the long-tube...
Next up were the long-tube headers. We opted for stainless steel (PN BBK 16415), but chrome and ceramic-coated are also available.
To install the long-tube headers,...
To install the long-tube headers, the steering shaft must be disconnected from the steering rack and moved aside.
Grieves installs the BBK mid-pipe...
Grieves installs the BBK mid-pipe to the long-tube headers.
O2 sensor extension harnesses...
O2 sensor extension harnesses are included with the purchase of the long-tube headers.
A final run on the chassis...
A final run on the chassis dyno yielded 397 rwhp and 378 lb-ft of torque, but there were much larger gains in the mid-range.