my first post, hello everyone! my corolla is a sedan so it *might* be different to stivo. i put in a new system this year and the speakers in the doors are 6.5" the speakers are easily removed, unlike american corollas which have speakers riveted to the doors. my new head unit is single din therefore i had to install an extra pocket. the pocket is genuine toyota part and cost $18.00. the pocket can only be installed on the bottom thus your head unit on the top. there are gaps along the left and right sides and these are filled with another toyota genuine part which cost $15 per side. if you do not like having 4 parts (head unit, pocket, left side blanking, right side blanking) you should purchase American International stereo installation kit specially order from jb hifi or garys car audio. the part is toy-k960 and this is one piece, matches dash contour and factory textured abs plastic. i think the cost is $40.00. if you need to change the interior bezel behind your side mirrors this cost $22 per side. you might change it to be able to install tweeters (surface/flush install, not hidden).