wanting to add a battery to power all of my interior show lights, guages and amp. do i just ground it and run a power wire from it to the other battery, or do i run it to the alt.? Thanks

One option would be to install a battery isolator which will allow your alternator to charge each battery as needed, with the starting battery having priority. Here's a setup similar to the one in my 92 RS.

ok thanks

hey thats pretty nice could you actually tell me what each of those objects are on there besides the batterys, alternators, and isolators.

It's even easier than that, if you are trying to increase your current (amperage), wire the batteries in parallel! Doing this will double the amps and you should have no problems.

You have three options.
One is to use a diode isolator, like what is in the pic above. Get one made for a GM. Good ones cost.
Second option is to just run them in parallel. This is the cheapest, and should be avoided. You can run into problems like the evil dueling battery syndrome.
The third option, and the one I would recommend, and an doing on my own truck, is solenoid isolation. This just puts a high current relay (solenoid) in between the two batteries run in parallel. This would disconnect the batteries with the car off. If you're clever you take advantage of the solenoids coils min pull-in voltage. You can run you're second battery down listening to the radio, and still start the car. You still get double the cranking current, and don't have to wonder if one battery goes dead, will I be able to start the car, or would it have killed the other battery too.