hey, i am thinking about purchasing a GS300 real soon and i was wondering about changin the factory deck to an aftermarket one. does it matter if i get the ML/Nakamichi deck or the standard lexus HU? i have right now a pioneer premier deh-p840mp and really wanna keep it, i have heard that the factory system has its own amp and that needs to be bypassed. i have a jetta right now and alot of people told me that it needed to be by-passed too but my headunit is workin fine with the factory amp.

how hard is it to install an aftermarket deck? will it work with the factory amp/speakers? help help help

thanx