Upgrading front stage for 2004 Lexus GS430 w Center Channel

[ChuckStakes]

I am seriously looking to upgrade my front and rear stage kids & highs. I currently have Lexus GS430 with mark levinson system and navigation. i believe I have to wire into the factory amplifier.I am currently looking i to the Morel Hybrid 602 for the front stage and integra for rear. I may go to the Elates but right niow the budget does not allow. Anyways I have some concerns. First, anyone recommend a processor that will take care of it along with the center channel. I have heard a lot of systems without the center channel and feel it makes a big difference so I would like to keep it. and may e upgrade it. Any suggestions would help. I figure I will build new door panels and seal up the doors with a second skin door kit along with ABS plastic. I will keep all speakers in factory locations but am looking for anybsuggestions I can get. IU would be willing to do a build log to show the progress. I will be adding to my sub stage which is an HD750/1 on a Jl Audio10w7AE in a ported inclosure in the trunk. I just don't have a clue where to start for factory integration.I figure an Audison Bit one and an HD600/4 for power, and Morel speakers. Thats as far4 as I have gotten. Like I said would love to do a build log to show any upgrades that have been suggested.