How do I install a sub in my Mazda 3 stock radio?

I have a 2004 Mazda 3 Sedan. I want a decent quality sub that isn't too much trouble to install and isn't too big AND want to keep the existing stereo system AND mount it in the trunk. What kind of sub is good for this and how much is all of this probably gonna cost?|||REMEMBER make sure you know the security code for you head unit before disconnecting the battery. Usually listed in the owners manual/log book. If not you can usually pay a small fee and get it again from the car manuafactures service centre but you will need proof of ownership (registration papers).





You can go to any of your electronic stores that sell car audio and choose a sub in a box and an amp that will suit your needs. Any will be able to be installed it is only up to your budget.





To install:


You will need to run a heavy gauge wire direct from the battery that is fused (best to buy an amp wiring kit with your sub and amp). The remote (activates the amp) will need to be run from behind the head unit in the car or off the key ingintion, if you dont want to mess with pulling head units out it can be run from the live wire that go to the cigarette lighter as it is activated off the key and is usually heaps easier to get at. It does not need to be very thick wire as all it does is trigger a relay in the amp to turn it on. The amp actually gets it power from the main thick wire that comes straight off the battery. The ground or earth only needs to be connected to the car body somewhere. Make sure you use some emery tape(metal sandpaper) to remove paint to expose bare metal to ensure good connection. Usually can do it somewhere where it wont be seen (back of seat or under carpet in boot). Before screwing make sure that there are no wires or anything important (fuel tank) under where you are putting the screws.





for your signal (music) you have a couple of options:





first option


you can get an amp that has high level speaker input - then all you need is to use the same wires that go to your back speakers and piggy back them and send to the amp.





second option


Also you can do the same thing by tapping into the speaker wire going to your back speakers but you can buy a small box that converts high level speaker input into RCA output. Then simply run RCA leads from the box to the amp. Usually around $40.





Third option


You can check to see if the standard head unit in the car has an RCA output. If it does then you can simply run RCA leads from the back of the head unit to the amp. Once again this step will require you to pull out the head unit of the car which I have found in newer model cars can sometimes be a little tricky.





Hope this helps and good luck!


Cheers


Luke