Do what 97 teg said. Just hook up the new rears to 2 channel and run it at 2 ohm stereo. As for running 3 amps, there's nothing wrong with that. I've done that in my old 94 Integra and had no problems. I'm doing that in my 99 Si right now, and now problems. If you were going to compete or something, then you'd worry about upgrading the alternator.