I run some 3" mids alongside the tweeters at the base of the A pillars in my car and for an old deaf head they certainly raise the vocal part of the soundstage and possibly reduce the smearing of vocals although with 6" door speakers a lot of the voice, particularly with male voices, is still coming from the door bottoms.
I run mine semi active as I don't have enough outputs on the Pioneer head unit so the 3" and 1" tweeters are fed from I think 1.1 KHz upwards to a passive 2 way cross over network that came with the tweets and original 6" mids... these are a bit of a lash up with Diamond Hex 6" mids in the doors, Dynaudio sealed back 3" mids and 1" Phase Linear tweets at the A pillar, yep all old school!
I'll be honest I'm always torn between 2 way and 3 way component sets but chicken out with the T6 as there's never a chance to go booming with Mrs Stay Frosty in the cab too, apparently at age 61 I should have grown up by now.
