Audio Systems: amp ground, sheet metal screw, metal frame

Question
i have a 96 for explorer . just installed a sub and connected all the wires . the amp is behind the rear seat and i cant find a good ground connection for it . a expert here told me to un bolt the seat mount and connect it there . which i tried last night . the problem is the seat mount doesnt seem to be metal and underneath it is the carpet so i dont think that would work to well . any other spots u guys know about ? ? need some bass . thanks for the help .  

Answer
Well, I have never seen a car where the carpet wasn't cut (like notched) around the seat bolts.  I the seats HAVE to be bolted directly to the metal frame to be safe.  what I would suggest is to take some sandpaper or one of those little wire wheel things that you can put on a drill and remove the seat bolt.  then all around where the bolt fastened to the seat, sand it until it shines.  then you'll know you've got metal.  sand the bolt down too, if there's paint on it, you'll get a poor ground. make sure where the underside of bolt would be touching the seat bracket its all nice and shiny there, and the treads too.
I think you'll get a good ground here.  if not you'll have to cut a flap in the carpet, peal it back, drill a hole, sand it on both sides of the car, and put your bolt through there, then lay the carpet flap back down over it.
make sure you use a bolt with a nut on the other end, don't just use a sheet metal screw or something just screwed in.  it has to be very tight.

Good luck!