If I had to do it again I would replace the front and pod speakers with kicker 4”.
then adding a sub was a huge improvement.
The kicker key is nice but not needed.
I did replace my rear speakers with 6.5”s and used the kicker key amp. But they still have almost no bass. I think it is still being blocked at the input to the amp.
I will say the Key did make the system louder. But I lost bass in the process. I need to replace the subwoofer with an amplified solution and then I think it will be good.
Just got the kicker key 200.4 installed today. The sound is WAY better and I haven't run the calibration yet.
So far I have Kicker 4" speakers in the dash, stock in the front panels and 6.5" in the Mabett pods in the back.
I have an 8" sub that I have yet to install, think that will level...