I have Kappas that I just pulled out of my last vehicle before trade-in. Kappa 60.7cs and 62.7i that I'll use the woofers from the components in the front doors and put the two-ways in either the back doors or hatch.
I don't anticipate doing it for a couple weeks, but I'll post up a little feedback when I do. Running all off the OEM JBL amp for now but agree with OP, if I do an entire system, I'll re-wire everything.