has an h800, running passive xovers and 4 6x9s take this advice with a grain of salt.... second thought dont take it at all. lets start by saying what will the tweeters be mated to are you using a dsp do your have capability of changing the xover are they going to be on 2 channels (left,Right) or 4 channels 1 foreach tweeter? What are you expecting from them? Do you have a midrange speaker playing 300-4k? Are you looking for vocals? Do you want a tweeter that can play down to 2500hz?
lots of variables here. If your have a loud spl set up a regular tweeter is likely useless to you. And Unfortunately super tweeters is what you will need.