You need to decide what you want your Mustang to do, and how much money you want to spend before you do anything to your Mustang. Do you want your Mustang to go faster, take a corner faster, sound better, or look better? Is your car a everyday street car, a weekend racer (play toy), or a dedicated race car? Do you care about gas mileage or whether the car rides like a tank? Perhaps the biggest question is how much can you afford to spend on your Mustang. You need to be realistic both on what you want your Mustang to do and how much you can spend on your Mustang. Within limits, you can have it all if you're willing to spend enough money. A carefully modified Mustang (naturally aspirated) can easily run 12 second quarter mile times, out handle a Corvette, and still get 20 miles per gallon around town. It will also still be much cheaper than that Corvette. Adding a supercharger or a nitrous kit to the same combination would easily run 11 second quarter mile times, on street tires. Get some magazines (5.0, Super Ford, and Muscle Mustangs and Fast Fords are all recommended) to both see what is going on, what is available, how to do certain modifications, and where to obtain (order) your parts from. Mail order is the way to go to obtain your new parts. It is both cheap and fast. Most parts will arrive within 3 days. One more comment on magazines is don't believe everything you read, especially with respect to advertisements. Advertisements don't lie, but they can be very misleading, particularly with respect to claims that part abc will increase your horsepower by xyz. Their claims are not based upon a reasonably stock Mustang engine, but rather a highly modified engine. In that case, changing the only restrictive part left will make a huge difference in horsepower. Unless your engine is highly modified, reality is that you will only get a small part of the horsepower increase that the advertiser claims.

          Weight reduction is very important. A lighter car is both quicker, will handle better, will have a higher top speed, and get better gas mileage. In particular, you want to reduce weight in the front of the car if at all possible. Every 100 pound reduction is worth 0.10 second in reduced quarter mile time at the drag strip. All other things being equal, if your car is lighter than your buddy's car, your car will be quicker, faster, and handle better. Take out things that you don't need in the car, such as the "junk" that we all tend to keep in our trunk or hatch area. Think about things you add to your car with an eye towards weight reduction, or minimization. Aluminum heads are 50 pounds lighter than cast iron heads. Chrome moly steel is much lighter than mild steel and things like strut tower braces are available in both varieties of steel.

          There are huge differences between the different year Mustangs. The best years for fairly serious modifications are the 89-92 5.0 Mustangs. If you have a choice, buy one of those. The first year for factory forged pistons and the factory roller camshafts is 85. The first year for the 5 speed was in 83, but it would not tolerate any serious power until 85 when it was vastly strengthened. The 5 speed received further improvements in 89 to handle even more torque. The first year for the 8.8 inch rear end, which is mandatory for any serious Mustang, was 86. The engine block was seriously strengthened in 86 over the previous years, except for 79 which was the last year for the old style thick blocks (definitely stronger, and heavier). The clutch was also upgraded to 10.5 inch (from 10 inch) and true dual exhaust was added in 86. The first year for the 11 inch front brakes, which should be mandatory for any 5.0 Mustang, was 87. The first year for the mass air sensor, except for California cars (88), was 89. The mass air sensor allows pretty wild modification of the engine while retaining reasonable idle quality and gas mileage. The 86-88 fuel injected 5.0 Mustangs are very limited on engine modifications unless you add a mass air flow sensor. The last year for factory forged pistons was 92. Without forged pistons, power should be limited to about 300 horsepower, but you can always add them when you rebuild your engine. The first year for sequential fuel injection was 86. The 84 and 85 central (throttle body) fuel injection system is junk from a performance standpoint. For a street car, sequential fuel injection is highly desired because the engine torque curve, driveability, and gas mileage are all far superior compared to a carbuerated engine. Having said that, relatively speaking the 86 engine heads are junk and should be avoided. The 87-95 heads are all the same and much better than the 86 heads. The 94-95 Mustangs handle better (factory stock) than the 79-93 Mustangs, but are also heavier and therefore not as quick.

          Another factor to consider is the body style. A convertible, while having certain obvious advantages, is heavier and has a weaker structure than either the coupe or the hatchback. The convertible therefore will be slower and not handle as well as the other two body styles. The coupe is the lightest (about 60 pounds lighter than the hatchback) and has the strongest structure. The coupe therefore will be the quickest and handle the best of the three body styles. The hatchback has the lowest aerodynamic drag coefficient of the three body styles and is arguably the sportiest looking. The hatchback is superior to the coupe for high speeds, but not in the quarter mile. One more comment on body styles is that the LX body style is lighter and has a lower aerodynamic drag coefficient than the GT body style. That means that the LX is quicker, has a higher top speed, and will handle better than a similar 5.0 Mustang GT. On the drag strip, a Mustang GT will need an additional 10-15 horsepower to keep up with an otherwise identical Mustang LX. The 94-95 Mustangs require an additional 15-20 horsepower to keep up with an otherwise identical 79-93 Mustang because of the weight difference.