For the stock radio use I had high level inputs (speaker wire) going to the amp. For grounding you can buy a little mount to bolt in the trunk, giving you more placement possibilities. Rem (remote) wire I got help here hooking it up to the power antenna. Search for posts by me for that help. Here's what I did for power:
>Entended battery terminal >Autozone for about $3-4
>Inline fuse
>Remove that clip-screw (easy) and take that cover off temporarily to access the grommet.
-I went through a grommet about 10" below the arrow. I had to put the car on ramps
and go through the other side with a coat hanger pushing up from underneath the car (acutally a friend did this).
-Power run along drivers door trim
-Connect it to the 12V source after connected the GRD/ REM.