I plan on installing my db component tweeters in my A pillars as far forward (aimed opposing headrest which matches 6.5 midrange in door) as possible in order to get reduce the path length distances as much as possible. The only problem with this location is that the instrument panel goes really high and will interfere partially with the sound out of the driver side tweeter. If I were to put the tweeters closer to me on the A pillar (very sharp angle), thus avoiding dash issues, I fear the stereo image will suffer because the near tweeter will be significantly closer in proportion to the far tweeter.
A big issue with installing the tweeters far back on the A pillar is that reflections off of the dash and windshield may interact resulting in cancellations because of comb filtering. I plan on laying down a dash cover (I'm thinking suede) to prevent the windshield-dash interactions.
Have any of you used a soft cover on the dash in order to prevent comb filtering when installing tweeters/midrange speakers up high?
Also, I'm going to be running the tweeters active, how low can the db tweeters be safely crossed at 24db/octave?