vy rear speaker replacement, help.

[cpbait]

hi everyone, i have a vy srz1, it has aftermarket 6x9 pioneer speakers in it that are playing up, i want to replace them with 6" splits in the rear, and put the tweeters in the rear pillar(custom put in), is this possible? will i have any problems with gaps on the sides from where the 6x9's sat?

also i want to put 6" splits in the front doors and rear doors and get the tweeters put in to the pillars or doors(custom done by a good automotive trimmer) will this sound good with a single or 2 twelve inch subs all subs and speakers running of amps, i go to the drive-ins a bit so want a good sounding stereo for the drive-ins and day to day music, going to use pioneer speakers to go with headunit and clarion or pioneer amps, has anyone done this before?

does anyone know what the new pioneer subs are like for confined spaces and how much? thinking of fitting on sides of boot so still have majority of boot space. i have a single 12" alpine sub i might use or get pioneer subs to go with the rest.

any help and recomendations (speakers to use and good automotive trimmers in melbourne) greatly appreciated, Ben.