headers

i have a 1997 gst with turbo hardpipe greddy type s and i was wondering about an exhaust manifold if i got one of these would it make my car and louder or not?

The exhaust manifold wouldn't make the car noticably faster or louder. If you want loud, buy turbo-back exhaust. If you want obnoxiously loud and raspy, get a dumped o2 tube, too.

The exhaust manifold (header, not headers, since it's an inline 4) isn't a logical early bolt on for turbo cars.