your ground should be the same size as your power cable and NO longer than 18 inches like i said drill a hole as close to your amp as possible and bolt it there make sure you get the paint off and i suggest after you get it all done spray paint over it that will keep it from corroding

does the 3.8 have the junction box on the pass side fender if so bolt your power there greenarrow is right your alt will make the amp "whine"

i also suggest a ground loop isolator(noise eliminator)

i did install audio for like 2 years i do know what im talking about

 

The only thing about these cars is the body isn't all that good for stereo componets, it's a composite of steel and other metals that suck for conducting a normal amount for a stereo system. I homerunned my ground, all the way up to the battery and my system benefitted a lot from that. I would say if you can find someplace that the metal is very think and scrap the paint off, you could even soder the groud to the body and then paint over it. If you only have the sidepost battery, then I would move it to the positive terminal and that should fix the major part of the buzzing, you may still have a little until you get a loop iso or get a battery with top and side post and run your positve to the top post.

 

Do what i said first to if its a problem on the amp side or the hu