Just finished today... used the Audison "bitone" processor to go btwn the stock radio and the Jl amp... Its a bit pricey but the sound is amazing.. High end learning curve.. you have to have a comp. or laptop to process the sound its brand new so they are still hard to get.. jl makes one called clean sweep probably better if your gonna do it yourself.. if your in NY I could hook you up with my guy
Why bother with all that? Just buy an aftermarket headunit (Navi or not), hook up the Class II interface between the truck and the radio, and then use the pre-outs on the radio or the unused speaker level outs on the Class II interface adaptor to hook up your amp and subs.