now to the best of my knowledge i have 2 6x9'* in the rear deck and 1 4x6 in each front door. so a 4chan amp would work.

I don't know if you already know this or not.. But a lot of people will just upgrade there front speakers, then get subs and disconnect the 6x9'* I haven't done this yet, so I can't speak from personal experience but I've been reading around a lot on the internet and from what I've found out 6x9'* just ruin the sound stage.

what about replacing the rear 6x9s with a set of 4x6s?

something like this in both the doors and rear deck.

Pioneer TS-P462 (tsp462) 4" x 6" Speakers Car Speakers Car Audio Car Audio, Video, & GPS Navigation - Sonic Electronix

There is a plastic housing between the 'frame' and parcel shelf that is the shape of a 6x9 speaker so i don't see how you could mount a 4x6 to it without chicken wire and duck tape! Why would you use those anyway? I'm sure you can find 6x9'* for around the same price if that is the factor.

that is why.

im i better off going with the 6x9s and the 4x6'*? or 4x6s all around? i dont mind making a bracket or 2 to make the 4x6'* fit in the 6x9'* place.

im going for sound clarity more than anything here. if the 6x9s are gonna mess up the sound stage and ill take some time to make a plate to fit the 4x6 in there.

well i have 3 way 6x9'* in my ride, 4x6'* and a 12" sub and it sounds awesome, very clear vocals, highs, mids and lows when i want it. Everyone is going to have their own opinion on this topic but from personal experience and from the way my stereos past and present have produced, there'* no down side to using a good quality 6x9 speaker. They can generally handle a wide range of frequencies and the higher watts that aftermarket stereos produce without distortion.

i really dont know about 4x6'*. I would think they would end up just doing the same thing as 6x9'*. The reason that 6x9'* will supposedly mess with the soundstage is because they do alot of the same things that the front speakers do. I don't know enough about the topic to argue a point, but that is just what I've read. If I were you I would go over to caraudioforum.com and ask for some advice there. They are some very helpful people, just read the stickys before you post :p