Building an 850+ HP S550 Mustang Is Easier Than You May Think

By Brett Foote - November 25, 2019

Latest Coyote platform gives longtime Mustang fan the easy, ultra-powerful street beast that he’s always wanted.

I’ve always been a big car person, but the Mustang holds a special place in my heart. You could probably trace that passion back to the day I was born and brought home from the hospital in a ’66 coupe. Or maybe even before that, when both of my parents worked at a Ford dealership. Regardless, I’ve owned quite a few cars and trucks over the years, but Mustangs have always been my favorite. But after my last failed effort at resurrecting a too far gone Foxbody, I wanted to do things a bit different this time around.

I wanted to buy a Mustang that was already in good shape (gasp!). Something that I could simply get to work modding instead of having to cut out and replace rusty body parts and rebuild the engine. But my previous home simply didn’t provide me with the space to store anything other than my F-150 and my wife’s car. Once we moved, I sought out a house with ample garage space. And I eventually found it.

Months later, I was driving by my local Ford dealership when I spotted a Lightning Blue 2018 GT Performance Pack 1 sitting out front, dirty as could be. I pulled in and noticed that the dealer was already offering some pretty decent discounts, since 2019s were already on the lot. A few hours later, I struck a deal and took it home.

My First Mods

Needless to say, I had done a lot of planning in my head prior to actually buying the car. I had seen how so many people were able to achieve 500 wheel horsepower with simple bolt-ons. So I foolishly thought that this would tide me over for a while. Thus, after only days of ownership, I immediately voided my warranty with a VMP E85 tune. I also installed a JLT cold-air intake, Corsa long tube headers, and a Corsa Xtreme cat-back exhaust.

There were only two things I hated about the ’18+ Mustang in its stock form. The sloppy shifter, and the stock clutch pedal spring with its invisible engagement point. So I ditched those in favor of a Barton Hybrid 3 shifter and Steeda clutch spring. I then attacked the suspension by installing Steeda Ultralite linear springs, along with a BMR cradle lockout kit and vertical links.

Those mods quite literally transformed the way this car drove. I especially loved the new shifter and clutch feel, which was more like the old T5 that I had become accustomed to. But even though the car was now making good power, I still wasn’t quite satisfied. It might sound strange, but the S550 is an incredibly stable car compared to the old stuff I’m used to driving. It’s so nailed down, especially with the mods I performed, that it didn’t feel fast. Even though it most certainly was.

To Whipple or to ProCharge?

So I began looking at various power adders. At the time, there were a few folks running superchargers and turbos on their 2018+ Mustangs, but not a lot. My choices boiled down to twins, Whipple, or a centrifugal blower like a ProCharger or Vortec. At first, I liked the idea of the ProCharger because it was easy to install and cheaper. But the more research I did, the more I realized that I wanted more power throughout the power band. I didn’t want to have to rev the crap out of the engine and then worry about losing power if I let off to shift. Which would also obviously be an issue with a turbo setup.

Meanwhile, the couple of Whipple cars I had come across at this time were making impressive power. Especially the Stage 2 version of the 3.0-liter Gen 5. A Black Friday sale sealed the deal, and I placed my order. Unfortunately, I had to wait quite a few weeks before it actually arrived. But during that time, I conceived a plan. I realized that if I was going to tear the front of the car off to install the blower, I might as well go ahead and upgrade the oil pump gears and crank sprocket. Whether or not that’s truly necessary is up for debate. But it’s cheap insurance against total engine failure, regardless.

Time for a Tune

Another thing I learned in my research was that Whipple’s supplied tune was perfectly fine, but ultra-conservative. And that’s certainly not a bad thing if you’re worried about pushing the limits of your stock Coyote bottom end. Me, well, I’m a bit more power-hungry. So I enlisted a local shop, NWA Streetworks, to do a custom dyno tune on the car. The owner, Robert Lee, is well known in the area for doing quality work, and he specializes in later-model Mustangs. So that was a no-brainer.

At the time, I was hoping for around 750 at the wheels on pump gas. I didn’t want to do a return-style fuel system just yet, which would enable me to continue to run E85 and extract another 100 or so hp. After all, the clutch, driveshaft, and axles are still stock. I was already worried that I’d blow them all up, post-haste, after the Whipple install.

Prior to installing the blower, we did some baseline pulls with the previous setup. The car did pretty good, laying down 469 hp and 450 lb-ft of torque. Not as good as some similar setups out there, but not bad by any means. So my expectations were somewhat low moving forward. Nobody, including Lee, could have predicted how things would turn out in the end.

After dialing things in, Lee gave me a call and asked me to guess what the Mustang did on the dyno. I, of course, said I hope it did 750.

He said, “how about 857?”

I nearly lost it. Granted, this lofty number was achieved using an E30 mixture. There was a little E85 left in the tank, so he mixed it up just to see how far we could push the stock fuel system.

Still, an incredible result for an otherwise completely stock motor. Max power came in at a relatively low 7,200 rpm, with a peak 683 lb-ft of torque at 5,400 rpm. After running through this fuel mixture, Lee changed up the tune for 91 octane pump gas, as we can’t get 93 octane in my area. The car still exceeded my expectations, laying down 780 hp and 630 lb-ft of torque. That’s an incredible leap over the previous setup, and most similar setups. Lee attributed much of it to the headers, which seem to work exceptionally well with the supercharger.

Needless to say, my Mustang is an animal to drive now. Unfortunately, the closest drag strip is around 2 hours away, so I haven’t been able to track it yet. So before I make that trek, I want to upgrade the axles, driveshaft, and clutch, as well as get a drag pack with bias-ply tires so that it can hook. Hypothetically speaking, it shouldn’t (doesn’t) hook very well on the street, even with 305 Nitto N05 tires out back.

Above all, my latest Mustang is a just another testament to the 3rd gen Coyote platform’s capabilities. With a new fuel system and E85, it’s destined to make north of 900 hp. And I’m only running 12 pounds of boost, too, so there’s room to grow there as well. Of course, every bottom end has its limits, even the mighty Coyote. But in the near future, I’m more than willing to explore them. And when I do, I’ll be sure and share the results of that science experiment with you.

Photos for Mustang Forums by Brett Foote