uh...before you listen to overflow's suggestion about ditching the components, why don't u see what you can use? Components don't come cheap that's why. I'm assuming that the tweeters are a component system and not just tweeters alone cuz that just sucks. So what you want to make sure first is to see if the 6.5" on the front door panel and the tweeters are connected to a crossover. If the 6.5" spkrs aren't part of the component, then u could buy a new system.

What I'm suspecting is that the original owner had everything hooked up to a 4 channel amp. When he sold it to you, he removed the amp and just connected the original audio wire to the crossover, that's why your tweeters are still going. So take part the door panel and see what's going on. If you don't know how to take the panel apart, check out http://www.morningz.com/mz/integra/audio.asp.

Hopefully all you have to do it buy a 4 channel amp and reconnect everything. Man that's a long task. G'luck! post updates