Well then there ya go!
Just a little more challenging on your labor but that's probably worth it.
So long as Cadence is actually worth the money (I don't know the name to speak of their quality).
Just remember the old saying that usually comes true eventually.
"If it sounds to good to be true it probably is"
I looked at one 6.5" Cadence component speaker and it says it requires a 3" mounting depth. The Polk speakers I have say 2". You should check the depth of your doors (with the windows down) to ensure 3" depth will fit.