Official FAQ!

1. Can I use factory wiring with aftermarket speakers?

The simple answer, yes. The complicated answer, yes and no. It all depends on what factory system you have and what you are trying to accomplish.

For instance, if you have the MACH 460 system, there are a lot more wires and amps because there are more speakers. The Ford factory amps handle all the crossover activity internally, so if you add an aftermarket speaker to the factory amped system, you will be limited to those frequencies sent on that wire. This could damage the speaker. This is where you should avoid using the factory wiring, and buy yourself an amp and run new wires to the crossovers that come with your new component speaker set.

If you have the regular factory stereo with 6x8's in the doors and rear deck (convertibles too) then yes you can use the factory wiring because each of those speakers is getting sent full signal and the speaker itself is handling the crossover activity.

A third possibility is if you are going to use the factory wiring while using an aftermarket amp. You can run the outputs of the aftermarket amp to the front of the car and then tap into the factory wiring via a wiring harness adapter. Several models are offered depending on the type of factory system you have. It does make it easier in most cases, but generally if you have the MACH system, you should plan on running new wires directly to the speakers.

2. Do I need a ported or sealed box for my subs?

This all depends on what the sub's manufacturer requires. Some subs work better in sealed enclosures and some work better in ported enclosures. It’s best to ask a local shop for advice because even the slightest adjustments in size of the enclosure as well as the length and diameter of the port (if any) will yield different sounds coming from your subs. This is called "Tuning the box". Your sub should have come with a tech paper giving you tips on the proper type of enclosure and its size in order to fully maximize your sub's output. Also a sealed box will give you a tighter sounding bass where a ported enclosure will give you more of a deep "boomy" bass sound!

3. What wiring harness adapters do I need for my aftermarket headunit?

Scosche is one of the most popular manufacturers of wiring harness adapters, as well as installation kits for aftermarket headunits. Depending on your factory system, you will need different adapters. Check their website for Ford REGULAR system adapters by clicking here or for Ford PREMIUM systems click here.

4. I have "X" amount of dollars to spend, what should I do first?

No matter how much you have to spend, there are a few basic steps that should be performed in specific order, to guarantee you will have a great sounding system.

I you simply want more bass to your factory system; you can add an amp and a pair of subs (or single sub) in a box. You will need a line level convertor to be able to provide your amp with RCA inputs. You can tap into the factory system for signal. Check out for an article on how to do this.

Generally speaking, you should upgrade your headunit first, since it’s the "brain" and source of the system. A system can only be as good as its headunit, so don't go cheap. Alpine, Kenwood, Pioneer all make great headunits. Eclipse and Nakamichi are higher end headunits with better CD optics for cleaner sounds.

After the headunit, you can either add new speakers or a sub and amp. It’s generally best to buy an amp for new speakers and not let the headunit amplify them. But, you do what you can with the money you have. It’s best to do it in steps if you can't drop large amounts of money in one shot.

Here are some rough estimates for cost of EQUIPMENT only, not including labor from your local stereo shop:

Good Headunit, Alpine, Pioneer, Kenwood: $249-$500
Better Headunit, Eclipse or Nakamichi: $500-$800
New Speakers, component set: $250-$600 depending on brand
New Speakers, 2-way or 3-way: $99-$299
4-channel amp for speakers: $250-$600, $600+ depending on brand
Subs: Wide variety of sizes and brands, JL is one of the best - $250-$500 per pair, more if they handle more power or are competition grade, also more if bigger sizes are selected.
Sub Amp, 2 channel bridgeable: $250-$450, more depending on power needed and brand name

EBay has good prices on better brands, so check there often.

Good Brands: Infinity, JL Audio, Pioneer, Kenwood, Rockford Fosgate, Eclipse, Sony (speakers and amps ONLY), MB Quart, Focal, Boston Acoustics, PPI, Diamond Audio (HEX)

Higher End Brands: MB Quart, CDT, Dynaudio, Eclipse, Denon, Focal, Rainbow Pro, Adire, Audax, ScanSpeak, CDT

*Brands to stay away from (cheap): Pyramid, Jensen, Stereophonic, Sparkomatic, Legacy, Rockwood, Kenford, GPX

5. How do I get rid of engine noise in my system?

Engine noise is caused by interference from the car's electrical system that gets into your stereo system's signal wires. The speakers actually reproduce the interference and it sounds like a whistling noise that gets higher pitched depending on your engine RPM.

The most common cause is when power wires for aftermarket amps are run next to signal wires (RCA's) or speaker wires. Another common cause is a loose ground wire at your grounding point in the trunk area or at your amp. Other causes are from a bad RCA connection (perhaps a broken wire near the connector end) or even jumping signals between 2 amps that have different ground sources, commonly called a "ground loop".

Actual equipment can fail over time and induce ground loops into the system so try to unplug one thing at a time until you find the source of the interference.

To avoid introducing interference follow these simple steps:
1. Make sure your power wire and signal wires are run down separate sides of the car.
2. Make sure all amps share the same ground source. A ground distribution block is a popular and wise choice if you have multiple amps.
3. Make sure no RCA wires are strained by the connector end and if they have been strained during install, throw them out and get another set. Internal wiring at the connector can come loose and short out causing ground loops.
4. Make sure no one piece of equipment is causing the problem. I have heard stories of how an external crossover was old and the internal solder joints came loose and caused a bad hum in the system. Try to eliminate the source cables first, then equipment second.

6. How do I install an aftermarket head unit on my stock system?

The best way to add an aftermarket stereo to your stock set up is with a wiring harness. Don’t be cheap as they are only $20. This will save you a ton of time and a lot of frustration.

7. How do I add subs to my stock stereo?

It is fairly easy to add subs to your stock system. To start you need to find out if your amplifier (see below for determining what amp to use) will accept speaker level inputs. Speaker level inputs are a signal that is strong enough to drive a speaker without an amplifier (Basically a pre-amplified signal). If you don’t know if your amp is capable of this, just ask your stereo sales guy or check your owner’s manual. If your amplifier will not accept speaker level inputs, they you will need to buy a converter that will change speaker level inputs into line level inputs. Line level inputs are a signal that is not strong enough to drive a speaker, hence needing an amplifier. Once that is determined, everything else is the same. You will need to run power wire and a fuse from your battery to your new amplifier (see below for determining what size wire you need). I would recommend at this time that you spend the money and get a proper positive battery connection that accepts additional wires out. Put the fuse within 18” of your battery. The fuse on the main line is not to protect the amp, but to protect the wiring. Connect the power wire to the amp as per the specs. Now take a short piece of wire and connect it to a solid metal piece on your chassis. Connect this piece to the negative power wire input on your amp. Run the wiring down the left side of the car, as it is the easiest to do. Once your power wire is run, you will need signal. The easiest place to get signal on a stock stereo car is the rear speakers. Here you will need to splice one of the rear speaker leads so that you will have signal to the rear speaker and to your amp. Here is where your amp choice becomes an issue. If your amp accepts speaker level inputs, then you just connect the feed from the rear speakers directly to the amp as per the manufacturers specs. If your amp does not accept speaker level inputs, then you need to put your feed from the rear speakers into the line level converter, and then from the line level converter to your amp. Congratulations your amp now has power and signal. The only thing left is connecting the speakers. For the purpose of this discussion I will assume that you have your subs already mounted in a box. Mount your amp somewhere where it will get airflow and not be bumped around. Connect your sub speaker leads to your amplifier per the manufacturers specs and viola, you now have sub bass!

8. What amp to choose?

Choosing an amplifier is not as difficult as you think. Your amp choice is directly related to the subs that you have. For most people with 1 or 2 subs you can go with either a 1 (mono block) or a 2-channel set up. The difference between the two styles is the number of outputs (channels) they have. The other ways amplifiers are rated is by watts and stable to blank ohms. Watts is pretty simple. It is the power produced by the amp x how many channels it has. (Ex. 250x2 or 250x1) You have to be careful about watts though as some manufacturers tell you max or peak watts verses watts rms (continuous). The difference is huge, especially when peak watts are sometimes 3x the normal (rms) power. Ohms are a little more difficult to understand, but basically it is the resistance that the amp can withstand. Most car speakers are rated at 4 ohms. So most amplifiers power ratings are rated at 4ohm per channel. Almost all amplifiers are 2 ohm stable however. What does that mean? Well, when you connect more than one speaker (or more than one voice coil on DVC speakers) you change the ohm rating for that set of speakers. There are 2 ways to hook up a speaker. Series or parallel. With series, you basically add the ohms of the speakers together, and with parallel you divide the ohms of the speakers by 2. So if you have 2x4 ohm speakers and you put them in series you now have an 8-ohm channel. If you put the same 2x4 ohm speakers in parallel, you get a 2-ohm load. Now that you understand (hopefully) ohms, we can get back to power. Since ohms are a measure of resistance, the higher the ohms the more power is required to move the speakers, and vice versa for lowering the ohms. Now we have our same 250x1 at 4 ohms amplifier. Since most amps are 2 ohm stable we have a choice of how we want to hook up our 2x 4 ohm speakers. If we hook up our speakers in series (8 ohms) we will get an output of ~125x1 from our amp as we have doubled the impedance (ohms). Conversely if we hook up our speakers in parallel we will get ~375x1 from our amplifier. On a multiple channel amp, you could do this to each output. Now some amps will be 1 or ½ ohm stable, so you could load them down even further. There are also different classes of amplifiers. I won’t go into too much detail, but class AB is mostly for full range speakers (i.e. fronts) and class D is for subwoofers. Now as to weather to choose a mono or multi channel amp, it will depend on how many subs you are running and what ohms you want to play at. Generally the lower the ohms, the more power you get, but SQ (sound quality) starts to suffer. So for front speaker I would not go below the 4 ohm rating, but for subs 2 ohms is fine.

9. What subs do I get?

Choosing subs is a personal thing as everybody’s hearing is different, so will everybody interpretation of sound and what sound good will be different. Go to a store and listen to them! What I can do is explain a few common terms associated with subs. First is impedance. Basically the ohms of the sub (1, 2, 4, etc.). Second is SVC or DVC. SVC or single voice coil and DVC or dual voice coil. The voice coil is what gets hooked up to the amplifier to run the sub. IT is what the ohms are associated with. If you get a SVC 4 ohm sub, then the only way to hook up that sub by itself is at 4 ohms. If you get a DVC 4 ohm sub, you now have 2 voice coils and the sub will be hooked up as a 2ohm load or an 8-ohm load based on the series or parallel configuration. BE AWARE OF THIS DIFFERENCE as a DVC 4 ohm sub can’t be hooked up as 4 ohms. Power handling of a sub is just that, how much power RMS and Peak a sub can take from an amplifier. The diameter of a sub will tell you a few things about its characteristics. For example 8” and 10” subs tend to be more “punchy” and tight. Where as a 15” is more “boomy” and sloppy. The 12” is a compromise between the 10” and 15”. I know this is overly simple, but this is a simple FAQ :p. A box will make or break most subs so lets talk about them.

10. What sub box do I choose?

A SUB BOX WILL MAKE OR BREAK ANY SYSTEM!! A proper box can make a cheap sub sound good and a bad box can make a great sub sound terrible. I can’t stress enough how important proper box design is to any system. There are many types of sub boxes and I will go into detail on each of them. First, the most basic box, the sealed box. This box is basically a box with a hole cut out for the speaker and is airtight once the speaker is put in place. This type of box is characterized by its sound quality, high power handling, and smaller size. It is perfect for most installations where space is at a premium and/or high power handling is required. The next most common box is the ported box. The ported box is basically a larger version of the sealed box with a vent cut into the side. These boxes are characterized by their larger enclosure volume, but larger DB (decibel)(about 3 db worth) output, at the cost of reduced power handling. Having said that you can’t just go out and cut a hole in the side of your box to port it. There is more to it than that. Most sub manufacturers will tell you the size required for the box in addition to the size of the port and tubing to make the port required. The size and length of the port will determine the box’s tuning frequency. The tuning frequency will give a slight bump in DB’s at said frequency, but it will roll off at a very steep decline after that. Basically the subs will play sloppy, as they can’t control the sound frequencies below the tuning frequency. Most sub boxes that are ported are tuned in the 25-40hz (hz = hertz) range. Big SPL systems will choose a ported box as it offers bigger DB. You can also corner load a port to gain even more DB. The next most common box, but not used all that often is a bandpass box. It is basically a double-ported box with a built in crossover (hence the name bandpass). The sub sits inside the box, separated into 2 chambers. The front chamber is then ported to a set tuning frequency (about 80-100hz), and then the rear chamber is ported like a normal ported box (25-40hz). This gives the enclosure a double natural crossover and allows the sub to play in its most efficient frequency ranges. However like a ported box it is extremely hard to tune properly by yourself and should only be done by a professional installation facility. There are a couple more enclosure types, but if you need one of them, then you don’t need to read this faq anyway ;)

11.What size wire do I need?

Wire sizing is determined by how much power you are planning on making with your amplifiers. Add up all the amperage rating of your amplifiers and add a few more for good measure. Then select the size of wire that will support that much current draw. This will be for your main power line. Usually a good rule of thumb is go one step higher than you need as a precaution. So for most everyday 2-3 amp systems 4 gauge is plenty. Gauge is a term that relates to the thickness of the wire. Remember to buy a fuse for the main power line and put it no further than 18” from your battery. You can then distribute the power accordingly with a distribution block. If you have a 1 amp system chances are all you need is an 8 gauge main power wire. Anyway, most amps on the market will accept 8-10 gauge inputs. Check you owner’s manual to determine what yours requires. For speaker wire subs generally like 12 gauge or better and fronts are ok with 16 gauge or better.

12.What is a cap and do I need one?

A cap, or capacitor, is basically a small battery that helps your charging system keep up with you music. A cap is designed to stay by a power hunger amplifier in order to feed it the extra energy it needs when a heavy note is detected. Caps were designed to be a small, lightweight, and safer (as they are self contained) alternative to an extra rear battery. They are also designed to be discharged and recharged very quickly, unlike a battery. Thus taking a burden away from your already taxed electrical system. Caps work best when placed as close as possible to the amp in question. A cap will never be as good as an extra battery, but they are much easier to use. For example guys/gals with a huge SPL system will require more batteries not caps as a cap will not hold the electrical current required by those huge hungry systems, but for the average person who doesn’t want his/her headlights to dim on every bass note, they are not a bad idea in theory. There is currently a debate on weather they are effective at all, but the choice is yours even if it just gives piece of mind.

13. What are the stock speaker sizes?

• The stock speaker size on a fox body mustang from 87-93 is: Rear 5x7”/6x8” they both fit. Front doors 5.25” and the dash is 3.5” (I think).
• The stock speaker size on 94-98 is rear 5x7”/6x8” both fitting again. Front is 5x7”/6x8” in the doors and if you have a mach460 there is a 2.5” tweeter in the top of the door.
• The stock speaker size on 99+ is the same as 94-98, except for the new mach1000. I’m not sure about this set up as I have never worked with one.

If you have anything else that you feel should be added to this please pm me, if you have further questions post in the forum! A special thanks to The Engineer, Stylin Cobra, and GrandmasterK who wrote these questions and answers. Thank you and good luck!
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From somebody who competes in SQ and uses a ported box, if a box is ported, it can still produce tight bass. If the box is tuned properly and you have quality subs, you can play anything accurately. I use RF power series 10s in a ported box and it can play kick drums with amazing accuracy. You just have to have quality equipment. The differences between a ported enclosure and sealed enclosure are frequency response, a sealed enclosure will have a very flat response and depend a lot on size, ported enclosures will have more ouput at the frequency to which they are tuned and fall off sharply afterwards. Really, if you are looking for a box to fit your needs, I would check out a car audio forum like realm of excursion or, they can tell you exactly what you need to get the sound you want. No disrespect, but there is more than just these common assumptions to audio, which is why some people don't respect us in the mustang world who DO have extensive audio builds. Besides, some of your information is not correct, such as 8awg wiring being enough for single amp systems. Wiring size doesn't depend on the number of amps, it depends on the amperage draw from your amplifier and how much heat it will create in the line. My one sub amp would melt 8 gauge wiring. Some of this information is just flat out wrong and could possibly ruin the entire stereo system in a car.
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For the most part it is a good write up. Most people are very much a novice when it comes to car stereos and what was written will help clarify a lot of it. Yes we can nit pick various things but for the most part with what 90% of the Mustang owners wish to accomplish his information is right. Most Mustang owners will end up with some coaxials driven off a new deck and a small 200-400 watt class D amp with a sub. 8 AWG is sufficient for that.

And as stated a ported box can and will sound spectacular when tuned properly and the only real sacrifice is extension. I for one listen to music loud but also want it to be realistic so if there is a 15hz note in the recording I want the stereo to reproduce that. But both my cars stereos are kinda on the ridiculous side of expensive. My cheapest amp is $2000 and the door speakers in one were nearly $4000. :rlaugh:

I has issues. :(
For the most part it is a good write up. Most people are very much a novice when it comes to car stereos and what was written will help clarify a lot of it. Yes we can nit pick various things but for the most part with what 90% of the Mustang owners wish to accomplish his information is right. Most Mustang owners will end up with some coaxials driven off a new deck and a small 200-400 watt class D amp with a sub. 8 AWG is sufficient for that.

And as stated a ported box can and will sound spectacular when tuned properly and the only real sacrifice is extension. I for one listen to music loud but also want it to be realistic so if there is a 15hz note in the recording I want the stereo to reproduce that. But both my cars stereos are kinda on the ridiculous side of expensive. My cheapest amp is $2000 and the door speakers in one were nearly $4000. :rlaugh:

I has issues. :(

Pics or it didn't happen. :notnice: