Project MILF 2006 Ford Mustang GT Exhaust Install - Waiting To Exhale
Project MILF Gets The Works-Stainless Works, That Is.
From the August, 2007 issue of Muscle Mustangs & Fast Fords
By Frank H. Cicerale
Photography by Frank H. Cicerale
After Getting Project MILF...
After Getting Project MILF to ingest volumes of air with the FRPP Super Pack, we decided it was time to let the car exhale through a full-on Stainless Works exhaust system.
It's a pretty simple philosophy: What goes up must come down, and what goes in usually comes back out. In automotive terms, when you put more in (meaning air/fuel mixture), you usually get more horsepower out. That's what we had in mind with Project MILF.
If you recall, we took a Ford Racing Performance Parts Super Pack and put it on our '06 Mustang GT project car. The resulting boost from the Whipple supercharger lofted our mighty Three-Valve's rear-wheel power and torque numbers to 335 and 308, respectively. But that was only the beginning. Knowing that the blower was pumping in a higher volume of air, we wanted to upgrade the exhaust system to get the combusted mixture out of the cylinders quickly and effectively. That's why we decided to give Project MILF the works.
We dialed Stainless Works and ordered a pair of stainless steel long-tube headers along with a stainless steel after-cat exhaust system. The headers we installed were of the 1 3/4-inch primary tube variety, and they empty the exhaust gasses into 3-inch collectors. Included with the headers were high-flow cats and mid-pipes, front and rear O2 sensor extensions, and adapters to fit the 3-inch collectors to the 2 1/2-inch factory exhaust tubing, should we have chosen to do that. Of course, we didn't. Backing up the headers would be Stainless Works' 3-inch after-cat system, which showcases two high-flow mufflers, polished rear tips, a custom x pipe system, and all the hardware needed to make it fit like stock.
Before We made headway with...
Before We made headway with our exhaust upgrade, we put Project MILF on Crazy Horse Racing's Dynojet chassis dyno to get some up-to-date baseline numbers. With the FRRP-supplied Whipple blower whining, Project MILF cranked out 328 rwhp and 287 rwtq the day of the install.
One interesting thing about the system is that it was CNC-bent, so each one will fit the same way. An exhaust system's tubing is formed by one of three processes, those being pressure, mandrel, and/or CNC bending. Pressure bending involves placing a tube between a die and a hydraulic ram. The two are then pressed together, pushing the tube around a preselected radius, thus creating the bend. The problem with pressure bending a tube is that there's nothing inside of the tube to prevent it from collapsing or buckling. Not only does it look less than desirable with the bumps on the tubing at each bend, but inside, the corresponding rises impede flow. While this type of exhaust system is not great for performance, it's a quick and inexpensive way to equip vehicles with an exhaust system.
In response to the pressure-bent systems, the aftermarket developed mandrel-bent exhaust systems. To mandrel-bend a tube, a series of balls, known as mandrels, are inserted into the pipe when it's being bent. The balls are positioned and pulled through the pipe, thus supporting the tubing as it is bent. The smoother bends allowed exhaust manufacturers to make tighter radius bends. More importantly, with the tubing not being crushed, the system still flows well, even with the ability to bend the tubing to a tighter radius.
We Took one more look at the...
We Took one more look at the factory exhaust system, which-for what it's worth-was a decent system. Soon, the factory mufflers and tips would be set aside for the looks and functionality of the Stainless Works after-cat system.
Chris Winter of Crazy Horse...
Chris Winter of Crazy Horse Racing began disassembly by unclipping the connections to the O2 sensors.
There are a total of four...
There are a total of four sensors.
The Headers from Stainless...
The Headers from Stainless Works are of the long-tube variety and measure 1 3/4 inches on the primary tubes and 3 inches on the collectors. In addition to the headers, the kit also came with high-flow cats, midpipes, and all hardware (except for header bolts).
Next, Winter started taking...
Next, Winter started taking things apart by unbolting the head pipes from the exhaust manifolds.
With the front of the system...
With the front of the system unbolted from the exhaust manifolds, Chris undid the clamps and hangers holding the stock H-pipe in place, and pulled the assembly down in one shot. He then moved out back and took out the stock mufflers and the tubing that went over the rear axle.
As you can see, the Stainless...
As you can see, the Stainless Works muffler (left) is much smaller than the factory Ford muffler (right). While the outward appearance is nothing to get your shorts in a knot over, the main difference between the two mufflers is their internal construction.
Stainless Works has gone one step further with its systems, however. The after-cat system we installed on Project MILF is CNC-bent. Bending a tube in this manner is done entirely by a computer that controls both the position of the tube and the rotation of one bend in relation to another. Instead of having a person take care of bending the pipe, the machine cuts the tube to the desired length and then bends it perfectly. In addition, by CNC-bending the tubes, you can get away with using stainless tubing with a thinner wall for weight savings. Naturally, the stainless pipes have great corrosion resistance.
Additionally, our Stainless Works system came complete with an x pipe crossover. Obviously, the name for each component is a derivative of its shape; for example, an H-pipe looks like the letter "H," while an x pipe is manufactured in the shape of the letter "X."
A difference lies between the power and sound. An H-pipe has a deeper tone, one more in line with a classic musclecar, while the x pipe has a higher pitch. Both can make great power, but we've generally seen x-style pipes outperform the H-style exhausts.
Finally, we were forced to choose between long-tube and short-tube headers. Shorty headers are usually the closest thing you can get to a direct replacement for the factory exhaust manifolds. In addition, they are fairly easy to install. By comparison, long-tube headers dictate a more involved install, and there can be some clearance issues, depending on the vehicle in which they are installed. As for which is better, the long-tube or the short-tube, you will get varying opinions. The general consensus is that short-tube headers will improve low-end torque on lower-horsepower applications, but they give up some horsepower upstairs. We went with the long-tubes.
With The stock exhaust tubing...
With The stock exhaust tubing off, it was fairly easy for Winter to remove three of the four O2 sensors. Two were in the tubing following the cats, while the other was in the passenger-side head pipe. The final O2 sensor was located in the driver-side exhaust manifold. More on that debacle later.
With that said, we got the car up on the lift at Crazy Horse Racing, and in a little over a day's time, Chris Winter swapped out the factory exhaust pipe, cats, mufflers, and exhaust manifolds for the Stainless Works long-tube headers, high-flow cats and mufflers, and stainless steel pipes. One thing we noticed was that the installation of the headers is something you might want to perform with the car on a lift. It was rather involved, as we had to unbolt the steering rack, remove the dipstick, loosen the motor mounts, and raise the engine to give us enough room to slide in the headers. Also, we had to switch a few of the factory studs and bolts for regular Grade-8 bolts to avoid contact issues with the header tubes. The Stainless Works kit does not come with bolts, so you can either reuse the factory bolts or order aftermarket ones.
When we were done, we went back to the dyno. The results were interesting. The Three-Valve picked up slightly when it came to peak power, but it improved by as much as 20 rwhp and 25 rwtq at some points in the curve (see sidebar). And, keep in mind-this came with no additional tuning. If we could do it over again, we'd consider installing 1 5/8-inch primary tubes, as they would probably help MILF's engine make more power, especially in the midrange. Project MILF was also noticeably louder, though not obnoxiously so.
The Stock H-pipe is replaced...
The Stock H-pipe is replaced by the x pipe that comes with the Stainless Works system. An x pipe system provides more high-end horsepower than an H-pipe, along with a higher pitch.
Instead Of the semidrab stock...
Instead Of the semidrab stock exhaust tips, Project MILF will now proudly wear these shiny bad boys. With the tips being the last components of the system to go on, we glanced at them more than once while struggling to put in the headers.
To Ease installation of the...
To Ease installation of the headers, we had to unbolt the steering rack and loosen the motor mounts so we could raise the engine. In all honesty, once the headers were in, they fit quite well.
The High-Flow cat (left) that...
The High-Flow cat (left) that comes with the system is much smaller than the stock cat (right). Even though the high-flow cat is small in stature, it still allows the car to pass emissions (we hope).
The Stock-Diameter tubing...
The Stock-Diameter tubing (bottom) measures 2 1/2 inches, while the tubing contained in the Stainless Works system measures 3 inches. The increase in tubing diameter allows the exhaust gases to flow with less restriction.
After The rest of the exhaust...
After The rest of the exhaust tubing was removed, Winter undid the eight bolts that kept the exhaust manifolds in place. He was able to take out six of the bolts from the bottom but had to access the remaining two bolts from the engine compartment.
The real question is, did the increase in power translate into quicker times at the track? You bet it did, as MILF went from a previous best of 12.66 at 107.73 mph to a stout 12.47 at 110.00 mph, and it did so in worse weather conditions. Without a doubt, Project MILF has a presence on the road, though it's still docile enough to haul the kids around. Maybe we should change the acronym for MILF from Mustang I'd Like to Flog to Mommy Is Lightning Fast.
With The exhaust manifolds...
With The exhaust manifolds out, it was time to put in the long-tube headers. The passenger side was pretty straightforward, but the driver side proved to be extremely difficult. Once the headers are in, don't forget to lower the engine and tighten the steering rack and motor mounts.
After The headers were on,...
After The headers were on, the midpipes and the cats went on. Once the cats were on, the x pipe system and the rest of the tubing was mocked up.
Since Everything looked good,...
Since Everything looked good, Winter started to final-assemble the system one piece at a time. For the record, each piece of exhaust tubing is marked for either the right or left sides, as are the mufflers.
|Updated Household Budget|
|As We stated in our previous installments, we're keeping tabs on how much dough we are putting into Project MILF. After all, if we blow our paycheck on the car, how are we going to pay the mortgage? Keep in mind that this tally includes the cost of parts only. The original cost of the car and labor rates are not included, as there are variables to both figures.|
|PART ||MANUFACTURER ||PART NO. ||PRICE |
|Handling Pack ||FRPP ||M-2005-FR3 ||$1,299.00 |
|Super Pack ||FRPP ||M-6066-M463V ||$4,899.00 |
|Billet Oil Fill Cap ||FRPP ||M-6766-MP46 ||$ 44.00 |
|Valve Covers ||FRPP ||M-6582-3VBLK ||$ 269.00 |
|1 3/4-inch Long- ||Stainless Works ||M05H175 ||$1,542.40 |
|Tube Headers |
|3-inch After-cat ||Stainless Works ||M05CB3 ||$ 880.90 |
|Exhaust System |
| ||Total: ||$8,943.30 |
With all of the tubing in...
With all of the tubing in place, Winter tightened down the exhaust clamps one at a time. This is what the finished product looked like.
The Final piece of the puzzle...
The Final piece of the puzzle was the installation of the mufflers. The muffler hanger had to be removed from the frame on each side and swapped around as the brackets were welded on the Stainless Works muffler opposite the way they were welded on the factory mufflers.
Last But not least, on went...
Last But not least, on went the tips. Winter then aligned them using the good, old Ford tool: the beater bar. In actuality, he massaged the muffler brackets until they were in the correct position and allowed the tips to line up perfectly.
To Quantify how effective the long-tube headers and exhaust system were on Project MILF, we did a pair of before-and-after dyno pulls on Crazy Horse Racing's Dynojet chassis dyno. With the stock exhaust manifolds, cats, mufflers, and 211/42-inch exhaust tubing, the car pumped out 328.9 rwhp and 287.4 rwtq. After installing Stainless Works' 131/44-inch long-tube headers, high-flow cats and mufflers, and 3-inch pipe, MILF upped the power number slightly to 330.2 rwhp. The torque number saw a significant increase, as it moved to 304.8 lb-ft. If you do the math, that equates to a 1.3 rwhp and 17.4 rwtq increase.
The peak numbers do not tell the full story, however. If you look at the curves, the headers and exhaust system show an increase of both torque and power above the stock system starting at 4,200 rpm. This increase will help the car throughout the entire quarter-mile, and it's something you will definitely feel in the seat of your pants.
Now, you might be sitting there muttering to yourself, Didn't this car make 335 rwhp and 308 rwtq after the Whipple blower was put on? The answer is yes-and no. When the dyno tests were performed after the supercharger was on, compared to the runs made after the exhaust was installed, the air was much different. Cooler air makes more power, and that is what we had when we dyno'd the car with the blower. Even though the dyno compensates and corrects, it's a good idea to get a new baseline before each change. That's why we rebaselined MILF the day of the install. Nevertheless, the real dyno is the racetrack, so that's where we headed next.
With The exhaust in its final...
With The exhaust in its final position, Winter set about reinstalling the O2 sensors. Once the sensors were in, he installed the supplied O2 sensor extensions.
Remember That debacle we mentioned...
Remember That debacle we mentioned earlier? Well, here it is. In trying to remove the O2 sensor from the driver-side exhaust manifold, Winter realized that when it was installed on the assembly line, it was cross-threaded, thus ruining the sensor. Naturally, we got a new one.
Before He mated the tubes...
Before He mated the tubes to one another, Winter slipped the provided clamps over the tubing ends.
|Numbers, Numbers, Numbers|
|What would a MM&FF test be without some track times? After each install and subsequent dyno test, we rolled to Old Bridge Township Raceway Park in Englishtown, New Jersey, to gather some real-world track data. Consider this the start of the logbook. For the differences in e.t. and mph, the first number is the difference from the previous modification, and the second number is the difference overall from the baseline.|
|Baseline Run: 13.529/100.11 (stock powertrain) |
|Modification ||Best e.t./mph ||e.t difference ||mph difference |
|FRPP Super Pack ||12.661/107.73 ||-0.868/NA ||+7.62/NA |
|Stainless Works ||12.476/110.00 ||-0.185/-1.053 ||+2.27/+9.89 |
|Long-Tube Headers and After-cat Exhaust |
To Keep the exhaust system...
To Keep the exhaust system in the desired position, Winter used this support jack, which he placed under the center of the x pipe system. Once the system was tight, the support was removed.
Winter Felt that the system...
Winter Felt that the system was still a bit too loose for his liking at each joint, so he fired up his welder and tack-welded each joint. He welded only the back of the x pipe system because we are contemplating swapping out the factory converter in a future installment. If he was to weld each joint, he would only have to cut the joints at the front of the x pipe system later. Once the joints cooled down, he hit the welds with a wire brush and then some black paint.
While We picked up only a...
While We picked up only a little under 2 rwhp and 17 rwtq on the dyno, the midrange gains allowed Project MILF to hustle to a 12.47-second best with a trap speed of 110 mph. The Stainless Works headers and exhaust netted us a speed increase of more than 2 mph and a decrease of nearly 0.2 second when compared to what we ran with the stock system. Overall, with the FRPP Super Pack and the Stainless Works exhaust system, Project MILF has picked up nearly 10 mph and dropped more than a second in elapsed time.