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Beginners guide to performance modifications

Article by: GTRaptor Profile | E-Mail


New Mustang owners sooner or later will get caught in the MOD MANIA. Most of them will start with cosmetics but others will eventually want to get more performance out of their steeds.

In this guide we will try to introduce you not to the most popular but the more bang for the money mods.

SOHC and DOHC owners: Our 4.6 Section is under construction.


1. If your stang is not brand new the number one "mod" is TUNING, yes, you fist need to make your stang perform as expected or better than when it was brand new. We have a complete article about tuning HERE.

2. The stock mustang intake is pretty restrictive, to reduce its limitations install a K&N filter. For about $35 you can replace the ORIGINAL filter with a OEM fit K&N. If you can afford to spend a little more then get a COLD AIR SETUP, this you can buy or fabricate by following the steps in our ColdAir tech article.

3. This is where it gets interesting, most people will say get headers, others to get mufflers, X pipes or H pipes, etc. The main thing at this point is to improve exhaust without hurting performance which can happen if you select to big and exhaust system for your almost STOCK car. Our advice here is simple, get a set of free flowing mufflers, this is one of the most restrictive parts on the exhaust system and will free some hidden horsepower. Bigger headers, Xpipes or catbacks will cost you several hundreds and will not give the results you expect.

4. HEADS....are we nuts? you bet, we are nuts about power, heads are the BIGGEST restriction on the 5.0 HO. Changing to better flowing heads will net you gains close to 40horsepower. No other collection of "bolt-on's" can do this for the same amount of money. Just check this numbers:

Most common BOLT ONs Price HP HEADS Price HP
HEADERS $150   Iron GT40 $850 40
CATBACK $230   Alum GT40 Y $990 50
PULLEYS $70   Alum GT40 X $1,100 60
H pipe (off road) $150   Alum Edelbrock $1,100 55
MAF $180   Alum TFS $950 55
  TOTAL     Avg. Price Avg. HP
  $780 30 HP   $998 52 HP
  1 HP Cost $26   1 HP cost $19.19

As  you can see in the table the price performance ratio of the heads is way better than that of the most popular bolt ons, the HP figures of the heads are an AVERAGE of several numbers found on some magazines and manufacturers web sites, and we think they are pretty close to the real thing. Even a 40HP increase from heads alone is enough to justify their price.

Not considered in the table above is INSTALL PRICE, which will be almost the same for installing heads compared to all the bolt ons.

5. Next in our list is EXHAUST, after the heads are done the most restrictive exhaust part is the stock headers. In the OEM units the pipes are severely compressed where they are soldered to the flanges. This severely restricts exhaust flow (back pressure). The rest of the exhaust system is still OK for the amount of HP you have right now, probably a bit above 260 HP at the crank if your car is a 5 speed and about 250 if its an automatic.

6. Now we have to take care of the most restrictive part of the intake, the UPPER and LOWER manifolds. Here you will find lots of choices such as Long and Short runner manifolds of different brands such as FMS, Edelbrock, TFS, Saleen, Holley to name the most popular.

Our #1 Choice is the FMS Cobra intake, it has a good price/performance ratio and is the least expensive of all. But most of the other brands are pretty good and some offer more potential than the Cobra intake. If i were to choose another one i will surely consider the TFS and Holley units. The Edelbrock is also a nice intake, but in my opinion its damn ugly hehe.

7. Now that you took care of the U/L intake its time to get rid of the restrictive Throttle body. A larger TB will increase   performance as much as 15 HP with all the mods installed.

8. At this point your stock 19 pound INJECTORS are in their HP limit, a good choice is getting 30 pounders and a new fuel pump and MAF OR CUSTOM CHIP. These additions will help you calibrate your new combo to the new injectors. We recommend getting a chip tuned to your current setup instead of the new MAF. A good chip manufacturer will put your car on a Dyno to calibrate the new computer to get the most out of your combination of parts.

9. The Ignition system is now one of the weak links in the equation, with the added HP and fuel, a better coil will help you to make a bigger spark to burn the added fuel.

10. Last in our beginners guide is to replace the rest of the exhaust system, an H or X pipe here will free a few more horses and will get you ready for the next mods...probably a supercharger? turbo?

Here the choice is yours, the X will increase power about 5-8 HP more than and H pipe but it is also more expensive. X and H pipes can be bought for OFF ROAD use which means they don't have cat converters or street legal versions with high flow cats. The later are about twice as expensive but might be required in some states.

At this point, you 5.0 HO Mustang is close to 300 rear wheel horsepower, and of course it is more fun to step on the pedal but there are still things to consider. The suspension will need modifications, the same as the brakes to keep those horses under control.

Also, don't take this guide as your bible but consult others about their experiences, this guide is just a collection of steps WE think you could follow. But in reality you might want to skip some of the mods or NEED to skip because of money restrictions.

Buying used parts is good if you are on a budget, but buy only if you are 100% sure the part for sale comes from a reliable source. Headers, intakes, exhaust components are good used buys, you can easily tell if they are damaged. Heads are a bit harder to buy used cause some damage might not be apparent to the untrained eye.

Also remember that the SUM of HP gains for each part will not give you your total HP GAINS. Each part works in conjunction with the others. Think of the engine as a SYSTEM in which every part you install increases efficiency in relation to the other parts.

And last, have fun and by all means ASK ASK ASK others about their experiences.



This is a must read to all beginners seeking information on how and where to start modifying their pony.

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