when is the big 3 upgrade necessary?

i drive a 2001 honda civic lx (4 door). i am going to be putting a class D amp that has an RMS of 900 watts, and a 4 channel amp that will RMS at 200 watts, do you think i'm going to be in need of a big three upgrade. i'd like to avoid this upgrade at all costs, if i am going to need the upgrade, what could i change in my system to not require the upgrade? i know that was kind of unclear.  basically what changes can i make to my selcetion to make the big 3 upgrade un-necessary?

Cars aren't really supplied to support add-ons like big booming aftermarket audio systems.  You gotta do what you gotta do if you want the sounds.

Add a beefier battery to chassis wire, if nothing else, because it's generally a weak link in the circuit and your system will be using the chassis.  But you shouldn't be thinking of this as such a daunting task.  Did you read the Big 3 sticky subject?

This also has alot to do at how you have the amps set up, meaning what impedence and level you have the amps set to. Obviously an amp wired to 2 ohms will need more power than an amp at 4 ohms. Also an amp that has the gain set to 3/4 will need more power than an amp at 1/2. In my car, I still am using my factory alternator. I just had to replace the battery because it was the original from 01. When I first had my system in my car, the headlights dimmed a tad. Then I went and got a new battery and capacitor. Everything is perfectly fine now. The only time when I have alittle bit of problem is when my headlights are on alone with either the defrost or A/C. I have a volt gauge in my car and when I have those on, it drops below 13, BUT only when the car is at idle. Any other time, my volts stay above 13.9 to sometimes 14.4. Everyone on here says capacitors are a waste and that having an extra battery is only helpfull when you listen to your music alot with the engine off, but I have not had any problems with these 2 add ons affecting my alternator. The one way you can tell if your alternator is hurting, is to have a volt gauge. You would simply want to listen to your music and see if the volts jumps around alot. If at every beat your volts jumps down, then your alternator is stressing.

Back to the original question: when is a Big 3 upgrade necessary?  It is necessary any time you have added electrical loads to your system that cause the total current draw to get close to or to exceed the current carrying capability of the OEM wiring.  For some cars, that happens the moment you add ANYTHING to the car, even a new head unit.  For others, it happens only with larger amplifiers.

Bottom line is it is ALWAYS a good thing to do, not only to improve the sound system's performance but to protect you and your vehicle from burning down due to overloaded wiring.