Sorry, like other things unmentionable here speaker SIZE is of no issue, no matter. What does matter is not trying to drive speakers from a lowly 12 volts, or 24 volts effective ("H" bridge). What you need to FIRST do is make sure the speaker amplifier has a 100 to 250 volt source for speaker driving, the higher the better.

Many of the newer systems have mosfet DC-to-DC voltage up-converters, inverters, to accomplish this aspect.

just like real life, size does matter. you can't just stick any size speaker anywhere you want, it has to fit.

I just put a pair of 6 1/2 Rockford Fosgate Power(T1652) in my door`s and all I can say is WOW, the bass is so much better than any other 6 1/2 I have ever heard!!! I want to put the 6x9`s in the back deck but don`t know if they will fit anybody have any info??? What is the max install depth I can go ????

How did you get those 6 1/2" speakers back there? You had enough depth?