That can work really well if properly executed which most installers do not understand the basics of and normally further forward. Many championship winning installs have mids and tweeters at the base of the pillars or in the general area but it takes considerable testing and then tuning to get it right, not many people in the world would know how to do it.
In many vehicles mids and tweets in the kick panels is the absolute best place with midbass in the doors if a three way setup is done.
7 page article and more pictures on this link, the truck was not even fully tuned when reviewed and not done in a proper location, it was significantly better than the reviewer had the chance to hear but it was a very tight schedule to get to print on time.
http://www.raamaudio.com/1996-toyota-tacoma
Unfortunately I did not have the time to finish the mini Recaro rear seats, molded kick panel and console covers, etc...there were 5 amps, the processors and subs and more storage and space inside than stock, it was a considerable project to say the least.
My absolute favorite get it done, simple, superb if not absolute best results(championships have been won with this method) is to put the tweeters in the pillars 1" above the highest point of the dash aimed right at each other though in some cases a slight adjustment up and toward the listeners no more than 10 degrees works better.
Wire the tweets out of phase which is just reversing the positive and negative leads to help time align the arrival to your ears with the mids in the doors.
Doors, deaden them decently, use the stock locations, pretty simple.
Using low weight speakers and carefully applied deadening results in a low added weight and huge improvement in audio and in the case of the FiST, pretty mind blowing
Of course you need some amp power, sub, and tuning for the absolute best but just using the stock and not so great HU it will still be far better.
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The mag review was my Tacoma built in my back yard, outdoors close to the beach in La Jolla, $20k retail in gear but for less than 10% of that you can get incredible results
Rick