tweeters and woofers on different planes?

2013 prius c i plan on installing 1 set of ctx65cs components in the front door (woofers and tweeters both in the factory locations) but for the rear; i plan on mounting 1 set of ctx65cs woofers in the rear doors (factory locations) / and the tweeters, facing up, in [rear deck] (no rear tweeters came stock - there are no factory locations). i wouldn't have to flush mount them and i could aim them towards the front of the vehicle (probably on an angle aiming just above the top of the windshield). am i facing any potential adverse effects from doing this? are 2 sets of components going to cooperate? *even if i mounted the tweeters in the rear doors the same as the front doors? the main reason i am considering this is for aesthetics. any advice/feedback is appreciated - thank you

The higher the frequency, the more they need to be directed at the ear. And subs can essentially be anywhere (and merely mono). But others here are far more expert and experienced in these issues than I am.

just as oldspark mentioned, it is best to have the tweeters mounted as close as possible to the mid for the best sound. The high frequency tweeters are more directional, meaning your brain can easily pinpoint where the sound is coming from. If you mount them too far away from each other then the sound they produce will also sound disconnected from the system as a whole, and impossible to blend together without some kind of signal processor. If you cant mount them close together, id say within a 1 foot circle of the mid, then i think you would get better sound from a set of coax or just eliminate the rear speakers all together. plenty of people , including myself, only run front speakers in their systems because the rear locations are so terrible that it would only hurt the system as a whole to have them playing.

thanks for the feedback. i considered only running fronts; did a rough test of what it may sound like by removing the factory rear speakers - too empty for my taste. i think a set of coaxial speakers may what the doctor ordered for the rear doors. i haven't started looking into 6.5" or 6 3/4" coaxial speakers; any recommendations in the $150 range? *i've already purchased 1 set of ctx65cs components, i've been using them to determine the exact dimensions of the spacers i'll need.