Stage 3 Video: Project Fox Body – Performance & Handling

What’s the point of having the Cobra look without the performance to back it up? Stage 3 is less about looks and all about sheer power. We completed a top end motor overhaul on our 1993 convertible and had to revamp the suspension just to handle the extra horses. This Fox Body finally has the bite it deserves.

Stage 1 & 2 of our Fox Body build culminated in the savior of one abused Mustang from a future junkyard burial and its transformation into a sharp weekend cruiser any self-respecting Mustang enthusiast would be proud to drive. The conversion took a good deal of labor and vision to accomplish, but the results were drastic. Well worth the time and effort put into it. Folks, now it’s time to back up the intimidation factor that comes with any Mustang wearing the iconic Cobra emblems. It is finally time to load this snake with the performance-based venom it needs. Welcome to Stage 3 of Project Fox Body.

Top End Performance

When looking to add power to the 5.0L pushrod motor, the first place we decided to start was the intake. After adding an SR Performance cold air way back in stage 1, it was time to address the rest of the intake system. The top end of our motor received a full Ford Racing overhaul that included a Cobra intake manifold, Turbo-Swirl GT40X heads, the E303 performance cam and new valve covers for a bit of style. The GT40X heads were an advantage over the original GT40s that came on the original ’93 Cobra as the GT40X heads are lighter


due to their aluminum construction and have be re-engineered for improved airflow. The E303 performance hydraulic roller camshaft from Ford proved a great complement to the cylinder heads and tied together the rest of our intake mods quite well. The E303 is a very popular cam for street builds as it beefs up low to mid-range torque and has a mean sounding loping idle, without the risk of stalling. Also, for those of you wondering, the throttle body we elected is a 70mm piece by SR Performance.

Fox Body Mustang - Rebuilding a 5.0L Motor

Full Exhaust Overhaul

In continuing our Ford Racing fix, a set of ceramic shorty headers were installed in conjunction with BBK’s off-road H-pipe and Flowmaster’s American Thunder cat-back exhaust system. Those unmistakable Super 44 Series mufflers and BBK H-pipe, all with 2 1/2 inch mandrel bent piping, squared away our performance mods and provided the perfect amount of back pressure and exhaust flow we wanted. The only power mod still needed was our custom Bama 93 race tune to get all of our new parts dialed in and working in tandem with one another. More on the final results and dyno numbers later, let’s first take a look at our Fox Body’s inherent suspension deficiencies.

Flowmaster Cat-back Installed on 1993 Fox Body Mustang


We pushed the dial as far as speed, but we had to address our glaringly obvious suspension shortfalls before the Cobra vert could safely take on turns and hard launches. To start, SR Performance lowering springs and caster camber plates lowered the car’s stance about an inch and a half all the way around and firmly planted the car. New shocks and struts by Koni replaced the ancient stock setup and restored driver confidence in the turns and on bumpy surfaces. Because our car is a convertible, we had to address body flex and restore the structural rigidity lost in not having a solid roof. For this, we went with SR Performance’s full length, weld-in subframe connectors to tie the front and rear of our unibody Mustang together.

The Results
After all was said and done, we had finally reached a point where we felt our 1993 Mustang’s restoration was complete and it had the bite to back up the car’s eye-catching exterior. When we hit the dyno the results were as impressive as the entire transformation process itself. With increases of +130 horsepower & 107FT LBS of torque over the baseline dyno numbers, our 1993 convertible came in at an impressive 279HP and 317TQ to the rear wheels. Not too shabby for a 20 year old muscle car. Now, is this the last you’ll be seeing of our 1993 Cobra convertible? Maybe, maybe not.

It’s up to you to tell us where we should take this project next and maybe, just maybe, you’ll be in for a surprise Stage 4 edition of Project Fox Body.

total horsepower and torque numbers for Stage 3Horsepower increase in Fox Body Mustang from AmericanMuscle

Written by Andrew

"You're telling me it's got four wheels, two seats and goes faster than the speed limit? Good, I'm driving."


  1. Stage 4 should be rear and upper control arms!

    5 lug upgrade all around, with brake upgrade? Cobra front brakes? Cobra read brakes?

    Performance should be with a turbo or Vortech supercharger, even nitrous??

    I didn’t see you guys change the rear gears? Turbo = 3.55, Supercharger = 3.73, nitrous = 4.10

    Eibach sway bars!

    Roll Cage?

    Nice Cowl hood!


  2. great build , not to take anything from you guys , but there are factory built foxbody “cobras” . theres a member on that has one , he has all the documents from ford to back it. pretty sure its a 1/10 build.


  3. Thank you very much for doing this resto as I am taking on a very similar project! 😀 Great ideas as to what parts to buy, thank you!


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