Thanks for the replies guys.
See my problem is that I never messed with any lexus systems. This GS is my first car I've owned in 6 years because I haven't needed one living in Midtown Manhattan.
I used to install and compete for a place called Custom Auto Radio years ago but we mostly had hondas, nissans, toyota, etc. Stock systems were (well still are) a joke and were ripped out and replaced with quality components. This is the first stock system I've heard that was half decent. I'm going to keep it and only replace the low end.
Ideally, I would run a fused 4 gauge power wire on the battery side to the trunk for the amps power and the RCA's on the other.
SKP, are you saying that I don't need to run a power wire for an aftermarket amp? I am assuming the stock amp has it's own power source which will power a 500 watt amp? Are there Preamp (RCA's) there also?
Also, I think the W7 box should fit under the rear deck, no?
FJC