We previewed the Roush Performance lineup of 2015 Mustangs last fall, specifically focusing on the RS3 during our SEMA show coverage. Back then we struck up a deal with Roush to convert our own 2015 Mustang project car to Roush RS status. In January, we brought home Project 5-Liter Eater, our 2015 Mustang EcoBoost. We had spec’d the car with Roush, however, at the time of our delivery it was the dead of winter, and our schedules weren’t lining up with Roush’s for the conversion to take place prior to its delivery. This is a rare circumstance, and our request was a special case because we wanted to not only shoot photos of the car’s transformation for this story, but we also needed to do testing on our stock Mustang EcoBoost. With the arrival of spring, we were able to get our car to Roush for upfitting.

There wasn’t anything wrong with the styling of our 2015 Mustang EcoBoost, however, we were big fans of the look of the RS package at SEMA and took Roush up on their offer to build our car.

Staged Performance

We offer packages for nearly every level of enthusiast, from the RS in the V6 Mustang to the upcoming 670 horsepower RS3, there’s something here at nearly every level of performance. – Jay Velthoven, Roush performance

Roush offers multiple packages for Mustangs prior to their delivery to Roush dealers and then to customers. Packages start with the RS, which is for the V6. Stepping up to the RS1, this package is available for the EcoBoost. From there you can get a little wilder with RS2 which is available only on the Mustang GT. Finally, debuting this spring, is one of the baddest Mustangs you can buy from a Ford dealer, the supercharged 670 horsepower RS3. “We offer packages for nearly every level of enthusiast. From the RS in the V6 Mustang to the upcoming 670 horsepower RS3, there’s something here at nearly every level of performance” says Roush’s Jay Velthoven.

Assembly Line

By the time you read this, Roush will have finished upgrading their Plymouth, Michigan vehicle assembly facility to four operational assembly lines.Velthoven tells us, “We’ll be able to produce 300-400 vehicles per month to keep up with the demand the 2015 RS lineup has created.”

This is the last time we’ll see our EcoBoost as a stock Mustang. Prior to entering the assembly line, every car is washed by Roush’s cleaning crew. That’s a good thing since we braved a freak snow storm on the way here and the car was covered in ice and snow.

Each vehicle enters the build line after being thoroughly washed by the clean up crew. From there, the car passes through at least five more stations before going to final quality checks. Each station is manned by a technician, and much like a vehicle assembly line. Each technician has a specific job or jobs to do. Each tech also has all the tools, parts, and supplies to complete his assigned tasks.

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Each technician is a pro, and make no mistake about it, they’re car guys, not just an assembly line crew. Each team member can jump in and help out or even take over for one of his coworkers. No task is simple, but Roush has taken steps to ensure that each step along the way is consistent. Templates, guides, quality parts, and a well trained staff ensure that fit, finish, and the final product is consistent for every car that comes through the line. Prior to departure from the facility, every car is inspected and checked for quality. The entire process gives every Roush Mustang an OEM level of fit and finish, and is a product that stands out as unique, while looking like it came off not only the Roush assembly line, but the Ford line this way.

Left to right -The first station on the assembly line removes the rear bumper, to do this, the tail lights and part of the trunk liner are removed.

Functional Style

We take what Ford gives us and look at ways to improve it with our signature upgrades like the hood and side scoops, as well as improving the car’s aerodynamics.

Altering the styling of a car is a complex proposition. The factory lines need to be taken into account, and according to Velthoven, the parts that are changed should be complimentary to what the original designers intended.

Roush takes the lines of the 2015 Mustang, and in our opinion, sharpens them. It’s as though some of the the rounded edges have been filed clean, and given a new look that is knife sharp. While the styling dramatically changes (and we think improves) the appearance of the Mustang, it doesn’t alter the car in a way that it’s unrecognizable. “We take what Ford gives us and look at ways to improve it with our signature upgrades like the hood and side scoops, as well as improving the car’s aerodynamics” says Velthoven. The final product is decidedly Roush’s signature of building upon the foundation that Ford rolled off the assembly line.

Top Row: Left: The next station preps the trunk lid for the spoiler and hood for the scoop. The underside of the trunk lid is marked with a template. Center: Holes are then drilled in the underside, these are used to access the bolts for the spoiler. Right: This apparatus and a separate one similar to it are used to drill the holes in the top of the trunk and hood.

The hood is drilled for the hoodscoop, the drill guide not only ensures every car is drilled the same, it also captures the metal shavings to prevent damage to the exterior finish and reduce mess at this station.

The upgrades are also designed to be functional. There’s more here than just good looks in the styling department. Roush engineers worked to make these components functional, improving many aspects of the Mustang’s body. Ford’s Aerodynamicist was actually brought in to analyze the changes that Roush was making to the car. “The aerodynamicist concluded that the changes didn’t negatively impact the car in any way, and the spoiler does actually add some downforce without a significant increase in drag” says Velthoven. The front grille is another example of this. Airflow to the radiator, (and the heat exchanger on RS3 applications) is dramatically improved by utilizing a larger opening in the lower portion of the fascia.This also increases airflow to the EcoBoost intercooler in our case, and according to Velthoven, the lower portion of the radiator is the hottest, so this should improve vehicle cooling.

Left: Our trunk lid post drilling. Center: The top of our hood after drilling for the new hoodscoop. Right: Since Roush becomes the manufacturer of record for each car they install a RS package on, they're also responsible for corrosion related to any parts they alter. All the holes that are drilled are painted with a sealant to prevent corrosion.

The factory shift knob is replaced with a white Roush shift knob.

It’s easy to get carried away when restyling a car. “We don’t want it to look over the top or poorly done,” says Velthoven. The parts look like they could have been planned in the original design by Ford. The fit is excellent. The finish on the painted parts also matches the OEM color.

Optional Upgrades

Internal Quality

Roush has its own manufacturing facility for its parts. We took a tour of the facility, and were able to check out these parts being built. Everything from the fascias, to the smallest parts of the body kit are built here, some parts requiring as much as 3,000 tons of pressure to mold. Building their own parts like this, allows Roush to maintain strict quality control, and consistency with their manufacturing. It also allows them to develop parts more rapidly, and to handle any manufacturing concerns prior to them causing a production problem.

Aside from the standard RS1 package, Roush offers a slew of upgrades for each stage. In our case, those upgrades included a new set of Roush wheels, 20×9.5-inch with 255/35/ZR20 Hankook Ventus V12 EVO2 tires all the way around. This cast aluminum wheel is an all new design for the 2015 Mustang and available in either raw polished or painted silver. In our case the raw polished wheels really ties together the color scheme of the car, matching the silver accent in the rocker stripe to the wheels. “The wheels are a new take on the five-spoke theme that we’ve always used. They’re a little more Euro inspired. The raw polish finish is also new this year, giving the wheels a techy appearance” says Velthoven.

V8 powered Mustangs can get an upgrade to 20×9.5-inch wheels with Cooper Xenon tires, 255/35 front and 275/35 rear.

Three forms of identification are present on all real Roush models. The passenger side door jam, under hood on the driver side support, and on the dash where the Mustang Since 1964 plaque is normally located.

We also got our hands on one of the first sets of Roush gauges. The build crew replaced our stock gauge faces with Roush logo and font faces. Other options we added were the Roush hood scoop, side scoops, and window scoops.

Top row: Left and center images: The next step on the assembly line is removal of the front bumper. Far right: The under car tray is modified for the new Roush bumper.Bottom row: Left: Our front end with no bumper. Extension harnesses are installed at this stage for the fog lamps. Center left: The fog lights and marker lights/turn signals are transferred to the all new Roush bumper. Center Right and Right: The new Roush bumper is installed.

Roush also installed their all new high flow exhaust, that is prepped for their upcoming active system. -We’ll be installing that as soon as it becomes available.

We opted for Roush’s new stainless steel axle-back exhaust system that is prepped to accept its upcoming active exhaust. This is a set of dual tip mufflers, giving the rear of the car an even more aggressive flavor. “The mufflers come with a block off plate installed on the open passage, which keeps them quiet to meet federal sound levels for new vehicle drive by. The plates are easily removed by owners, giving the exhaust a sound that is closer to Roush’s race mufflers,” says Velthoven. The plates are also easily reinstalled, and when Roush releases their new active exhaust system with the RS3, we’ll be able to upgrade and go from quiet to rowdy with the flip of a switch, or by using a profile in the Roush app paired to an iOS phone.

There are more options available than just those we selected, and some options even vary depending on which stage the car is.

Left: A fixture is used to modify the rear bumper. This preps the bumper for installation of the Roush lower rear valance. Center: The new Roush wheels installed on our car in raw polished finish. Right: While we were up front snapping photos, there was a crew quietly working on the rear of the car to install the modified rear bumper.

Test Drive

Our hoodscoop is set in place using a combination of bolts through the holes that were drilled earlier and double sided automotive adhesive tape.

Top row: Left: The Roush deck lid panel is installed. All the power tools used have the torque preset to make sure everything is tightened properly. Center: The new spoler is ready to install using bolts/studs and adhesive double sided tape. Right: The finished rear section of the car. Bottom row: Templates are used to install the side scoops and badges.

Since we didn’t alter the suspension at this time, the driving experience isn’t that different from our standard EcoBoost. Cruising down the road, even with the exhaust plates removed, the interior of the car isn’t noisy, and the exhaust doesn’t drone. “We spent a substantial amount of time developing a muffler that would give enthusiasts the sound they were looking for, without any of the unwanted in-cabin noise that can cause stress and fatigue while driving.” Stand on the throttle and you can definitely tell this car has an exhaust note. With our EcoBoost, the turbo spool noise sounds great through these mufflers, and you can definitely tell there’s reduced back pressure and some better turbo response.

The quarter window scoop is installed. Like all Roush parts it has an identifying number that is recorded in the build log. The quarter windows receive a black decal prior to this installation to hide that number.

The final exterior station installs the Roush stripes and badges. In our case that's the hoodscoop stripe in matte black, the rocker stripe, and the side badges.

We had some concerns about how visibility would be impacted by the new hoodscoop, and the total loss of the quarter windows. However, we never used the quarter windows while driving, as it required too much twisting, and there wasn’t much visible there anyway. Visibility intrusion by the hoodscoop is minimal to nonexistent, its integration to the hood is just the right height, and doesn’t make a difference at all driving down the road.

Our car is one of the first to get the new Roush gauge faces. After disassembling the dash, the instrument cluster and Performance Pack gauges have their faces removed and new Roush faces installed. Gauges are tested via computer to make sure their back to their zero point prior to installing the instrument cluster back in the car.

Our RS1 EcoBoost sits at the Roush Quality Control station waiting for final inspection before being sent to the customer -in this case us.

Although we’ve lost some sidewall in the tires with our wheel and tire upgrade, the Hankook tires ride very well. They also provide plenty of grip and bite at all four corners. Road noise from these tires may actually be less than the OEM Pirelli PZeros on our Performance Pack equipped car.

Top Row: Our EcoBoost stock. Middle: Post Roush. Bottom: The first and last view the competition sees.

Everywhere we’ve taken the car so far it turns heads. We get thumbs up in traffic, and plenty of questions wherever the car is stopped. Quite simply, this car looks like nothing else on the road, and like no other Mustang. Roush has done a phenomenal job with this package, and we can’t wait to get it out on the autocross and track to see how it looks in motion through the camera lens.