I was thinking of using a passive highpass filter for the tweeters. Not sure about the brand, but all the one's I am looking at are 8 ohm. Is there a way to design a passive highpass crossover (more of a protection circuit) that would drop the impedence down to 4 ohms instead of 8 ohms? If this doesn't work, what about wiring 2 pair in parallel (1 pair in kicks and 1 in the Apillars). Use some soft of passive blend knob to switch between each pair). That would give me a 4 ohm load and be able to use tweeters in kicks, while still having a pair in the dash to avoid the "rainbow" effect.