Well I am soon going to order my system. Viper 2500d, 13.5" JL audio w7, MMats pro 6.5 components, Viper 200.4. Two amps and a whole lot of watts. Will I need to upgrade my alternator or anything else? I know I am also getting a Optima Yellow top, just dont want to spend alot on the rest of the electrical stuff I may need. This all going in a 92 SC300.

 

take your factory alternator specs and see what the output is. then figure you will use the a/c, lights, wipers, and various electrical including turn signals and that leaves you with only about 1/4 of the alternator reserve left. if you dont think you will ever be using these all at once, wait until the next time it rains. you will.

now take your systems and add all the amps rated currents up. sub amp fuse, mid amp fuse, head unit fuse, ect ect. take the total number and subtract 40%. the 60% left over is the nominal amperage you will be using when it's cranked. is that figure larger than the last 1/4 reserve in the alternator? I bet it is, and by far.

using this system you can figure out exactly what alt and battery will be right for you.

That's not a good sign. you need to be prepared to have a system BEFORE you get one. otherwise you are going to start tearing things up. If it were ME, i'd upgrade the electrical system and prepare yourself to take on an audio system down the road. ..... i know, not a popular opinion. Problem is though.....you can't pull 200 amps from something that only puts out 140. it's like running a low cfm fuel pump on a high output engine....everything in line is going to suffer.