i have a 2000 gt and wanted to know if anyone knows what belt size to use if you don't wanna run the a/c

unfortunately, i do not. There is a system to use. Take a piece pretty solid un-stretchy string, wrap it around everything you want to use in the best way possible, count the number of ribs you need on the belt, go to the parts store and they should have a way of finding you the correct size.