Performance Modifications to the Mustang GT

I’m about 5K miles from the expiration of the manufacturer’s warranty on my 2012 Mustang GT and I’m considering some performance enhancements. I plan to keep the car for a while–in fact it’s one that I may hang onto even after it’s time to buy another vehicle for everyday driving. So if you were starting with a stock GT, what modifications would you consider and roughly how much do you think those modifications would cost?

You are driving a car that has over 400 HP from a 300 Cu In motor. That is a phenomenal feat of engineering.

I suggest that you stick to mods like a new head unit (stereo) or suspension mods.

I’d begin with suspension and brake improvements first. there’s a LOT of stuff out there for this car, indeed there are companies that specialize in Mustangs.

Google “Mustang Magazine” and you’ll see what I mean.

For engine mods, you can start with a good catback exhaust system from a company like Flowmaster.

Even the Ford Company itself has a variety of goodies that can be found here. <<–linky linky


Since the sky is the limit on these cars, the only advice I will give is that you not overdo the engine if you go the additional horsepower route. The magazines and TV shows may talk about an 8 second car being a street driver but I’d take those claims with a grain or two of salt.

If you must tweak the engine I’d say stick with an exhaust system tweak and a mild supercharger.
The cost will vary greatly all depending but even that will run into the thousands of dollars.

On a somewhat related note, a local guy does some amazing things with the current generation of Mustangs. His Bonneville cars are putting out 1100 Horsepower on E-85 and his “soy cars” have been lightened due to the fenders, hood, seat covers, etc being made of soybeans.
Streetable they’re not.

You could install a higher flowing air intake kit, a higher flowing cat-back exhaust system, reprogram the computer, and even remove weight from the vehicle so it launches faster off the line.

But none of this comes into play and has an effect until you’re at Wide-Open-Throttle. So you have to ask yourself, how often will I be at WOT where I can actually benefit from the added costs for these modification? And if you add these modifications you feel you have to drive the vehicle harder to take advantage of these modifications. This just results in using more gas and wearing the vehicle out faster.


The Coyote is one of the great engines out there, I’d leave it as-is. While a high flow cat back exhaust system might get a few hp at wide open throttle, the ones I’ve heard are LOUD. They’d wear me out. I’d put my money into the suspension and tires. But get what’ll work for you, 30 series tires might handle a bit better, but the ride could be punishing.

FoMoCo did a LOT of work before releasing the 2012 GT 'Stang…You will have to spend a LOT of money to achieve even a modest performance improvement. Everything already is high-flow and low-restriction…Yeah, supercharging will do it, but engine life and reliability will suffer…You will probably have to use 100LL avgas if the puffer is active or lower the engines compression ratio…You will also greatly diminish the value of the car…Mustangs that have been hot-rodded can be very difficult to sell…

I have a Kenne Bell supercharger on my 03 GT. Expensive, but forced induction is the best overall value when you consider the gains for the money spent.

Make sure you know your insurance options before you modify the car. Some (many?) auto insurers won’t touch a modified vehicle. I’m sure you canfindinsurance, but it might not be with your current insurer.

Lets look at one very common mod for the engine, the CAI (cold air intake). If you decide to plunk down a couple hundred on one of these, first do a timed 0-60. Its best to do this at a track that has “tuner” time slots where your time is accurate. Then install the CAI and run the time trial again. After the great disappointment, see if you can get a refund on the CAI.

You will notice that on the stock air intake duct, there are little appendages, tubes or cavities that go nowhere. These are engineered specifically to your engine to break up shockwaves that occur to the incoming air at various RPM’s under certain conditions. The CAI does not have these because it is not engineered specifically to your engine. It is only engineered to fit under your hood. Also the oil in the filter element messes up the MAF sensor and throws off your F/A ratio.

I know someone who took a car that ran 0-60 in 7.5 seconds, and after putting on a CAI, new HP factory cams, factory HP header and cat back exhaust, managed to raise the 0-60 time to 9 sec at a mere cost of around a loss of 4 mpg and about $2 grand.

Great comment, @keith - this model Mustang as has millions spent optimizing the power output and flexibility. It’ll be very hard to improve without going to super/turbo charging.


Those cavities you speak off are there to quite down the air intake, that’s their primary function. Most people don’t want a loud engine, so the manufactures engineer their intakes to A. Be cost effective, B. Be quiet, and C. Provide enough airflow for the engine. For an aftermarket CAI, it goes. A. Power, B. sound, and. C. cost.

Also an oiled filter is nothing to be afraid of. I had a K&N filter on my Bronco for 200k miles and never had an issue with the MAF, likewise I have K&N CAI on my F-150, it’s been on there since I bought the truck ten years ago and again no problems, and I have a K&N filter on my daily driver Mustang GT, it’s been on for 60k miles and again no MAF problems. The MAF problems you hear about with oiled air filters and MAFs are 99% of the time people clean them and grossly over oil them. That’s when the oil get’s on the MAF sensor. But it’s a problem with the user, not product. If you clean and reoil correctly, your MAF sensor will be fine.

Also if you add a CAI, cams, a header and exhaust, and you don’t get your ECU tuned properly, you’re going to have problems. Some cars like the 05-up Mustang GT’s basically require a tune even for something as minor as a CAI. And some cars respond to CAI’s better than others, cars with forced induction generally respond very well, but lower displacement N/A engines typically don’t.

Also if you go the drag strip, you’re not getting 0-60 times.

The noise you hear in the intake ducts is caused by pulses of air crashing into each other. With straight tubing, you get standing waves of air that can enhance performance at some RPM’s and inhibit air flow at others. The cavities dampen the standing waves.

You are right about the 0-60 times at a drag strip, but you can do it with your own stopwatch at the raceway. Of course if you have money to burn, you could get a fifth wheel setup like the car mags do. I only mentioned using a local track for safety reasons, and you have a nice flat straight away for consistency.

Not legal to change equipment between the throttle and the cat on recent cars. Lots do, but not a good idea if it is inspected.

You’re not going to get any significant improvement from engine without complete disassembly and re-engineering, at a cost of many thousands of dollars. Ford has an interest in making these engines as powerful and efficient from the get-go.

Forget about your 0-60 times, you should be concerned about total 1/4 mile time and trap speed. It’s what happens after 60 that makes it fun. I’d look at wheels and tires, possible suspension modifications to save weight but decrease weight transfer on acceleration, and overall lightening of the car, especially under the axles. 1lb of unsprung weight is equal to 10lbs of sprung weight. Or at least that’s what they used to say.

You could also see if someone makes an underdrive pulley set-up for your engine. This will change the ratios of the items driven by the serpentine belt, running all of them slower for less drag.