Mustang Modification Guide

Mustang Modifications

By MG (Smike)

Have the mod bug? Want more from your Mustang? Whether for competition or enjoyment, you might want to modify your Mustang. If you are not really sure where to start, the guide below is meant to give you some ideas of where you can start.

Categories: Engine, Drivetrain, Suspension, Tires/Wheels, Brakes, Weight Savings



93 octane / Panel Filter / ECU Tune* / Short Ram Intake (Cone Filter) / Axle-Back / Cat-Back / Headers / High Flow Cat or Cat Delete / Supercharger (SC) or Turbocharger (TC) or Nitrous Oxide (N2O)
93 Octane:
Part: 93 octane
Why: 2011+ ECUs have many advancements with adaptive timing and knock control. ECU will adapt to 93 octane and run more timing and correct fuel for it. 4-6 wheel horsepower gain and 3-4 wheel torque increase.
Why Not: No reason not to let the car advance timing.
Cost: $2-4 more expensive per tank.

Panel Filter:
Part: K&N filter PN: 33-2431
Why: The 2011+ has a tuned intake and cold air snorkel. Ford designed the air box from the factory. Gaining horsepower and more importantly to them – miles per gallon. However, the OEM air filter can be restrictive to air flow. The K&N unit is a freer flowing panel. Engine will have to work less to pull in air. Result is quicker throttle response and more horsepower. Filter will also last a lifetime. Can be cleaned and re-oiled.
Why Not: None really. No ECU modification needed.
Cost: $50

ECU Tuning:
Part: SCT or Diablo Tuners
Why: 2011+ ECUs have many advancements within them. 2 wideband oxygen sensors. And adaptive timing and knock control. Automatic transmission shift points and firmness. But a 113 limiter due to OEM driveshaft limits. Reprogramming will rework timing and fuel tables. Optimizing them for modifications and over the OEM programming. 15-25 wheel horsepower and 10-20 torque gains. Limiter removal. And A6 transmission shift adjustments. You will also gain a few miles per gallon.
Why Not: Requires use of 93 octane for best results. 113 limiter removal means you can run at a higher speed then the driveshaft (and some tires) are rated to. Both should be changed for safety. NOTE: You should retune after each major modification. Some tuning shops have lifetime tuning.
Cost: $350-500

Short Ram Intake (Cone Filter):
Part: Varies
Why: Revised intake charge line from filter to throttle body for smoother airflow. Quicker throttle response. 5 wheel horsepower more once tuned. Most use filters that will last a lifetime. Can be cleaned and re-oiled. Added intake suction noise.
Why Not: If untuned for SRI, the MAF readings will be incorrect. ECU will think there is a problem and pull timing/fuel. You will lose power. ECU modification required. IAT – intake ambient temperatures. Dyno testing is done with the hood open and large fan blowing air into the intake. In the real world, even with a heat shield protecting the cone intake element from the motor, the car will take in hot air. Hot air is less dense. Less dense air makes less power. If you drive in very hot areas or stop/go traffic IAT will become worse. OEM airbox and cold air snorkel are well designed. 5whp increase for cost of intake is not a good ratio. Note: for a closed induction system (supercharger or turbocharger). If intercooled the density of the charge are will be changed.
Cost: $150-400

Axle-Back Exhaust:
Part: Varies
Why: OEM mufflers have very little sound. v6 boasts a wonderful v6 howl. Different muffler types give you different types/levels of sounds and resonance. Freer flowing internal designs will free up some back-pressure and increase horsepower/torque by a few more. No retune needed.
Why Not: Some can be very loud in cabin or drone at certain speeds.
Cost: $400-600

Cat-Back Exhaust (and Mid-Pipe):
Part: Varies
Why: In addition to the axle-back muffler change, changes all piping from catalytic converters to tail. Factory exhaust has a cross-over piping section (not X design) to balance the exhaust banks OEM. X style cross-overs have more flow than H styles. OEM has flattened sections to tune for vehicle noise and power. Cat-backs have near constant diameter tubing. Increase in flow and decrease in back-pressures. Some use lighter materials for weight savings.
Why Not: Some can be very loud in cabin or drone at certain speeds. Removing the harmonic tuning in the OEM exhaust might increase cabin drone. ECU should be retuned if back-pressures have been changed.
Cost: $450-1500

Part: Varies
Why: Engine exhaust ports to catalytic converter section. Two types – short and long. Both replace the factory cast iron headers. Have individual exhaust runners into the collector. And offer coatings to help temperature transfer. Short headers are easier to install. Longtube offer more scavenging and increase horsepower and torque more. 15-30 wheel horsepower and torque can be found with headers.
Why Not: Longtube installs can be tricky. ECU must be retuned.
Cost: $450-1500

High Flow Cat or Cat Delete:
Part: Varies
Why: Catalytic converters can be heavy and flow restrictive. High flow cats still will pass emissions in most areas and flow at higher rates (less back-pressure). Cat deletes remove the converter all together.
Why Not: ECU must be retuned. May not be emission legal in your area. Rear oxygen sensor will need to be tricked or adjusted if system is modified or you will get a check engine light.
Cost: $100-300

SC / TC / N2O:
Part: Varies
Why: Incredible power gains often 150-300 more horsepower/torque.
Why Not: ECU must be retuned. May not be emission legal in your area. Other modifications will be needed to make the whole system work optimally. If done wrong or something goes wrong engine life could be reduced. Nitrous use is not street legal.
Cost: $5000+ SC/TC. $500+ N2O


Short Throw Shifter / Aluminum Axle / Safety Loop / Clutch / Flywheel / Torque Converter / Rear Differential Gear Changes / Panhard Bar / Rear Lower Control Arm

Short Throw Shifter/Bracket:
Part: Varies
Why: Decreased distance of shift lever for quicker throws. More positive feel. Bracket replaces OEM metal and rubber unit. No change in throw distance but will give you more precise feeling shifts.
Why Not: Not for everyone. Depends of what feel you like.
Cost: $250-350. $75-100 for bracket.

Aluminum Driveshaft:
Part: Shaftmasters –
Why: OEM unit is rated to 113 miles per hour. Past that there is a catastrophic failure risk. If you have retuned the ECU limiter this is a must. Shafts are also 10 pounds lighter. Less rotational mass frees up horsepower the motor now does not have to use to rotate the shaft. 8-10 wheel horsepower gains have been achieved.
Why Not: Recommend additional safety loop for street. NHRA requires a loop.
Cost: $450-550

Safety Loops:
Part: Varies
Why: Recommend or required if you have an aluminum driveshaft. Two types – front u-joint and mid shaft loops. Also stiffen chassis by tying in body points.
Why Not: None.
Cost: $150-300

Part: Varies
Why: Clutches are rated by torque. If you make more engine torque then the disc and pressure plates are rated to then the clutch will slip and fail. Note: OEM may be same unit as GT. GT unit is supercharger ready and can handle a lot of torque. Every system has its limits. If beyond its rating or overworked by the driver, the system could fail/slip.
Why Not: Full face disc is same as OEM style. Easy daily driving and engagement. Puck style and unsprung can handle more loads at the loss of drivability. Pressure plates have different clamping loads. Higher loads often result in stiffer clutch pedals.
Cost: $250-500

Part: Varies
Why: Flywheel is mated to engine and connects to clutch disc. Iron and aluminum versions. Lighter flywheels reduce rotational mass resulting in free power increases, quicker rpm changes, and shifts. The OEM unit is a dual-mass flywheel. Dual-mass is a hybrid that attempts at giving the driver good off the line engagement and a light feel. These can fail over time.
Why Not: Less flywheel mass makes car harder to get off the line. Shifting technique has to be good or between shifts can be jerky. Can stall car easier.
Cost: $250-400

Torque Converter:
Part: Varies
Why: Increasing the rpm stall speed on a torque converter will result in the engine reaching the powerband sooner. Result is quicker acceleration. OEM is 1500 rpm. Aftermarket can go from 3000 to 5000.
Why Not: Too high of a stall will make the car hard to drive on street. The transmission is set to lockup starting in 3rd gear. Not as much time is spent in 1st and 2nd, still something to note.
Cost: $700-1200

Rear Differential Gearing:
Part: Varies
Why: Quicker acceleration, quicker into powerband and application of torque. Base has 2.73. Performance Package has 3.31. Gear change options include 3.55, 3.73, 3.90, 4.10, 4.30, 4.56.
Why Not: Requires ECU reprogramming to correct MPH. Reduction in MPG. Requires additional parts for install (Ford 8.8 Pinion Bearing). Changes transmission behavior – less MPH per given RPM. Example is first gear will have a maximum of speed of 33 MPH (OE with 3.31 is 45 MPH). Requires more shifting. Automatics are required to correct the shifting and shift points. Be sure to calculate how the new ratio will modify your car.
Cost: $150-300

Panhard Bar:
Part: Varies
Why: OEM bar can twist and flex. If lowered you will need to adjust the bar since you have changed the rear axle geometry. Helps keep the rear axle located.
Why Not: Requires some tuning to get right.
Cost: $100-200

Rear Lower Control Arm:
Part: Varies
Why: Base v6 does not get the upgraded Performance Package LCA. LCAs help keep the rear planted for better acceleration and better cornering. Wheel hop is better controlled also.
Why Not: None
Cost: $100-200


Springs / Struts / Sway Bars / Camber and Caster Plates / Coil-overs / Front Control Arms

Part: Varies
Why: Quicker acceleration, braking, handling response, lower center of gravity, and MPG increase. Car will transfer weight more efficiently in acceleration and deceleration. Increase spring rates will give more roll resistance and increase the response of the car to driver inputs. MPG may be increased if the car is lowered. Less airflow under the car makes it more streamline.
Why Not: Some springs are dress-up parts. Not all have known rates. Some just lower the car. Car must be aligned after install. Camber and toe will be out of alignment. Panhard bar strongly recommend.
Cost: $250-300

Part: Varies
Why: Spring changes can take the OEM struts out of their internal valving and stroke range. Struts do not care where they stroke from. But they do care if they bottom out or have rates beyond what their valving can do. Aftermarket struts can be non-adjustable or adjustable for valving control. Driver can dial in preferences with adjustable units.
Why Not: Not for everyone. Advanced racing use type modification.
Cost: $500-850

Sway Bars:
Part: Varies
Why: Sway bars work to control lateral sway of the car and change how the car applies its grip. Bars can be adjustable or non-adjustable. Adjustable units can give the driver control to tune for weather or surface conditions at an event.
Why Not: Not for everyone. Advanced racing use type modification.
Cost: $300-600

Camber and Caster Plates:
Part: Varies
Why: Camber is the degree the tires are tilted inward. Caster is the degree the struts are tilted fore to aft. Camber is adjusted to keep tire contact patch to the road in high force turns. Too little camber and the tire will roll over on itself and contact patch will be reduced. Too much and tire will not reach its maximum contact patch. Caster changes the steering feel of the car. Increase caster and car will track straighter, have an increased steering feel, and improve corning camber. Decrease and car can become unstable at speeds.
Why Not: Not for everyone. Advanced racing use type modification. Every camber change will also change toe.
Cost: $300-600

Part: Varies
Why: Advanced springs and strut combo. Driver selected spring rates. Matched adjustable struts. Adjustable ride height. Dialed in for specific racing use.
Why Not: Not for everyone. Cheap brands are everywhere. High spring rates without though of vehicle dynamics. Advanced racing use type modification. Will require alignment for any camber or height changes. Very specific modification.
Cost: $2500+

Front Control Arms:
Part: Varies
Why: Advanced modification for specific racing use. Materials can be lighter. Less unsprung weight for more precise response.
Why Not: Not for everyone. Advanced racing use type modification. Will require alignment for any changes. Very specific modification.
Cost: $500+


Performance Tires / Light Weight Rims / Wider Rims / Semi R-Comp and R-Comp Tires
(See Tirepedia Page)

Performance Tires:
Part: Varies
Why: Increased acceleration. Decreased stopping distances. More lateral grip. Quicker steering response.
Why Not: Wear at a quicker rate then general street tires. Can be less effective in rain. Cannot be used in sub 40 degree weather.
Cost: $600+

Light Weight Rims:
Part: Varies
Why: Increased acceleration. Decreased stopping distances. Quicker steering response. Reduced rotational mass will free up horsepower.
Why Not: May not be as strong as OEM units. Can be damaged by potholes easier.
Cost: $1000+

Wider Rims:
Part: Varies
Why: To fit wider tires. Wider tires can have a larger tire contact patch, which will increase ultimate grip.
Why Not: May increase weight. More rotational mass. More tire contact patch will make car less responsive to smaller inputs.
Cost: $1000+

Semi R-Comp and R-Comp Tires:
Part: Varies
Why: Advanced racing use only tires. Increased acceleration. Decreased stopping distances. More lateral grip. Quicker steering response.
Why Not: Racing use only. Not for everyone. Wear at a quicker rate then all street tires. Can be less effective in rain. Should not be street driven.
Cost: $1000+


Pad and Rotor Upgrade / Fluid / Stainless Lines / Air Ducts / GT Brembos
(See Brake Rotors, Pads, Lines, Fluids, and Ducts Article)

Pad and Rotor Upgrade:
Part: Varies
Why: Pad material will give more friction coefficient (drag) will increase initial braking bite. Higher operation temperatures (MOT) will be more resistant to fading. See my brake article on rotor types.
Why Not: There are street pads and there are race pads. Each has their usage.
Cost: $200-500

Part: Varies
Why: Higher dry and wet boiling points. More resistent to boiling. Brake fluid should be serviced every 2 years. More if racing.
Why Not: Not for everyone.
Cost: $10-80

Stainless Lines:
Part: Varies
Why: Firmer pedal feel. More resistant to heat fade in hard use (racing).
Why Not: Not for everyone.
Cost: $150-300

Air Ducts:
Part: Varies
Why: Cooler pads/rotors/hub/wheel bearings = happer pads/rotors/hub/wheel bearings.
Why Not: Not for everyone.
Cost: $30-300

GT Brembos:
Part: Ford/Brembo
Why: Increased pad surface area. Increased rotor diameter. Aluminum calipers. More pad area to apply drag. More rotor area to heat sink. Aluminum calipers have more pistions and heat sink better.
Why Not: Not for everyone. Race use modification. Increased unsprung mass.
Cost: $1500


Spare Tire Delete / Rear Seats Delete / Light Front Seats / Carbon Fiber Parts

Spare Tire Delete:
Part: None
Why: 30 pounds removed from rear of vehicle. More storage space.
Why Not: AAA or other towing service recommended. Home made tire patch kit required.
Cost: Free

Rear Seat Delete:
Part: Varies
Why: 40 pounds removed from middle of vehicle. More storage space.
Why Not: No area for rear passengers (none really OEM either).
Cost: Free to $200

Front Seat Delete:
Part: Varies
Why: 40 pounds removed from middle of vehicle. More support for g-forces.
Why Not: Can be less comfortable. Not for everyone.
Cost: $500+

Carbon Fiber Parts:
Part: Varies
Why: Hood, fenders, doors, trunk lid — massive weight saving potential.
Why Not: Should be painted. Clear coated CF is known to yellow over time. Part fitment might not be OEM quality.
Cost: $500+