What material is the tweeter made out of? Silk dome tweeters work well more on axis and would work well in the doors or mounted closer/facing the listener more. If they're metal dome tweeters they typically work better further off-axis and reflect better without loosing high end detail so on the dash or in the a-pillars works well here. Very important to use the tweeters as they were intended to get the best results so mount them where they'll perform best even if it means a little extra work on getting them off/on axis.