The dash tweets aren't true tweeters, or that's not how they will be used. CDT calls them mid-tweeters, and they were actually designed to be mounted exactly like that in conjunction with the Soundstage setup, which I have. That's the centerstage setup, specifically designed for use as a centerchannel, and they recommend firing them off the glass in the center. They won't be given the full power of the rest of the tweets, they come with an adjustable crossover/level adjustment, so they can be adjusted down just enough to bring the imaging up.
Or at least that's the theory behind them......lol