Old thread but just did this install myself based on this thread. Installed the 3.5" speakers in dash and soundbar and then the KSC40 4" in the soundbar. Definitely sounds better. Also stuffed some polyfill under the dash speakers and inside the soundbar. The kickers fit fine albeit a little tight on the 3.5" and then I used the kicker plastic ring to install and hold the 4" in place it seemed to line up with that bracket with the existing holes. Pleased so far especially for the price of the 6 speakers.