I just got done swapping out both sets of door speakers as I felt they sounded pretty bad even with the premium sound upgrade which apparently is only the JBL Nano sub. I found the spec's for the similar Hertz speakers and ended up going with JL Audio C2-650x (6.5") for the front and C2-400x (4") for the rear. These run at similar watts and levels to the OE Hertz. Super easy install, took a Dremel to widen the openings a bit in the plastic housings, cut the pig tails and install new female ends for the speakers, and that was it. Made some changes in the custom equalizer settings and much happier overall with stock amp running them. Only think I may add is some sound deadening in the doors but so far so good. I have my OEM JBL sub almost turned down completely and may remove entirely if I put in an amp for the 4 speakers to get more out of them. Anyone find a good location to tap into all 4 speakers wires in one place yet?