Stealthy, 1,235HP S550 Runs Mid-8s In The Quarter

A quiet rocket ship. That’s what we thought the first time we witnessed Joe Holt’s Magnetic Grey GT blazing down the drag strip. The experience was calm and almost subdued, especially after a handful of 1970s-style muscle cars shaking the pavement all evening. Joe’s 2015 Mustang GT sliced through the air, making its speed almost unnoticeable.

Originally, I purchased the car thinking I was just going to do some appearance mods and leave the motor alone. — Joe Holt

In fact, you would probably wouldn’t guess there’s 1,235 horses exploding under the hood — at least not until you saw the 8.53 elapsed time on the board.

“Originally, I purchased the car thinking I was just going to do some appearance mods and leave the motor alone,” Joe said while laughing.

Being a hands-on guy and owning a private garage, he started out with a few quick bolt-ons including Ford Performance lowering springs, a Flowmaster cat-back exhaust system, and an off-the-shelf SCT Performance handheld tuner. But it wasn’t more than couple of months before he began researching turbochargers and superchargers.

“I needed a little more, so I thought, I’ll just buy a turbo kit and not do anything else — but that didn’t last long,” he confessed.

The first order of business was clicking the “Buy Now” button for a Limitless Performance & Fabrication S550TT twin-turbo kit. During the install, he knew the drivetrain would need a little backup, so he also swapped out the rear axles in favor of a set of Ford Performance axle assemblies, along with a Driveshaft Shop one-piece aluminum driveshaft. The interior gained a Watson Racing six-point roll cage and the fuel system topped off with triple, Walbro 420-lph pumps and a set of ID1000 injectors.

“After all the upgrades, I ran the car an entire year and I collected 176 time slips, ranging from 9.01 to 9.4 seconds in the quarter mile,” he said.

Two Comp Turbo 6466 units go unseen due to being cradled under the custom-built All In Racing Engines Coyote 5.0.

In late 2016, the Midwestern winter was setting in and to combat the cabin fever, he decided to push his car further. This time, he was going all in, so he began by stripping out the stock Coyote engine and sent it off to All In Racing Engines in Cincinnati, Ohio, for a complete rebuild, which included blueprinting, balancing, Molnar rods, and custom Race Tec pistons.

Meanwhile, Joe called on G-Force Engineering to ship out its 9-inch IRS kit that combines an upgraded Strange Engineering Pro HD housing and rear axle assemblies, plus he also opted for a G-Force aluminum one-piece driveshaft. While installing the rearend components, he pulled out the stock 6R80 automation transmission and sent it to Limitless Performance & Fabrication for a complete rebuild, valvebody upgrade and an upgraded Circle D, 6R80 Pro Series Stage III torque converter.

Joe Holt 2015 Mustang Mods

• Aerospace Components brakes

• All-In Racing Engines-built Coyote 5.0-liter

• BMR Suspension bushings, control arm bearings and vertical links

• Flowmaster cat-back exhaust

• G-Force Engineer 9-inch IRS

• LPF twin-turbo system

• Mickey Thompson tires

• PBD custom calibration

• Strange Engineeering Ultra HD differential

• Viking dampers

• Weld Racing wheels

The suspension was upgraded with components from BMR Suspension comprised of new differential bushings, cradle bushings, verticals links, and control arm bearings. Joe rounded out the suspension with a set of Viking adjustable racing shocks.

Once the drivetrain and suspension parts were installed, he set back the reconditioned Coyote was in the cradle. Joe then swapped out the previous LPF turbochargers for a set of Comp Turbo 6466s backed by larger ID1300 fuel injectors and a bit of customizing.

“After adding more boost I realized I needed a better intercooler, so I fabricated a custom air-to-water setup which so far, works very good,” he added.

Needless to say, fabrication is one of his many traits — along with automotive painting, which is showcased on the Anderson Composite carbon fiber hood that he color-matched to the rooftop in Tuxedo Black.

At first glance, one wouldn’t think this is a 1,235-horsepower Mustang. Joe’s intentions were to keep the car as natural looking as possible.

I love having a 1,200-horsepower car with navigation plus heated and cooled seats, that I get groceries with or take to the city for dinner. — Joe Holt

Lastly he bolted on a set of custom-painted, beadlock-style Weld Racing RTS 76 wheels wrapped in Mickey Thompson ET-R tires and peeking past the hubs you can see the Aerospace Components drag racing brake calipers.

Finally the car was ready for a new tune. That’s when he called on Ken Bjonnes of Palm Beach Dyno.

“We actually tuned Joe’s car remotely, which is fairly simple process for us,” Ken explained. “We also helped him dial it remotely during track testing to help make tune as effective as possible. Overall, Joe’s car is probably one of the most impressive cars that I’ve helped and he’s great to work with, because he’s just a regular guy with his own garage.”

All of the hard work and persistence shows with a most recent quarter mile time of 8.53 seconds at Gateway Motorsports Park in Madison, Illinois.

“I love having a 1,200-horsepower car with navigation plus heated and cooled seats, that I get groceries with or take to the city for dinner,”  Joe said.  “But overall, I couldn’t do all of this without the support of the suppliers and especially my fiancé who’s always helping me in any way possible.”

So what’s next for Joe and his Magnetic GT?  He says that currently he’s completely satisfied with the setup and its mods. But the Midwestern winter hasn’t showed up yet, so we’ll have to see if he can resist further mods.

About the author

Adam Riley

Growing up with a wrench in his hand, Adam applies his personal background of car building and racing into media content. With nearly fifteen years experience of motorsport photography, video and journalism, you'll spot him with a camera and laptop nearly everywhere he goes. To view samples of his work, visit or via Instagram @_theartofcar
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