Try re-positioning the tweeters into the footwell area pointing up towards the rear-view mirror.
Temporarily extend your cables and just try various positions and angles.
Here in th UK we use Blu tac to hold the tweeter in place whilst we try different positions and angles.
Not sure if you can get it over there, and before you ask what it is........
http://www.brainyencyclopedia.com/en...l/blu_tac.html 
