G'day from the Land of the Finns.
My -06 160SR has 6.5" = 165mm front and rear.
I changed to mine 2-way Pioneer to front and 3-way to rear. more in my blog => -06 Micra 160SR of Mika The Finn
"Apr 19, 2017
In last autumn I upgraded original speakers to Pioneer TS-G1723i 17cm 6.5" 3-way in rear, Pioneer TS-G1722i 17cm 6.5" 2-way front ones will follow when weather warms up in here. At same time I started sound proofing of noisy rear section in these vehicles, but yearly winter season with cold weather interrupted it. So whole winter time I had tiny Micra van, cause I removed back seat and interior rear side panels in order to do sound proofing Miraculously spacious van, when rear seat is off.
In addition on left side under drives seat nestles Pioneer TS-WX120A Active Subwoofer 150 Watt, I made a base for it from wood and this way it stays in place with out screws. Enough of sound system improvement to my preference & wallet
Under rear speakers I made anti rattle rings from 20mm plywood, old trick to get rid of rattle noises after new speakers have been installed. They reinforce speaker surroundings when speakers-thin body metal-plywood bolted all together.