3 way versus 4 way really depends on the music you listen to and location of your speakers. Highs are directional, unlike bass sounds, so they have to be directed towards your ears. If they are door mounted go with 3 way...you wont hear the difference. If dash or rear deck mounted then try the 4 way since the glass will reflect the sound to your ears...but this would be for ultra higjs in trace and classical music mainly.