3-way means it has three speakers in one. Most 6x9 speakers are 2-way or 3-way. Unless you have a really good ear all you need for really good sound is:

-good head unit (w built in amp, 4x15 or 4x25 watts)

-two 3-way 6" for front

-two 3-way 6x9 for rear

anything else is overkill. Start with this and if you think you need more add it as you go.