If your GT is a 96+, you actually have two cams.
Usually cams are matched to the combo. if you are looking for engine lope, just pull a vacuum line.
If your GT is stock, I'd invest elsewhere first, such as a plenum and throttle body.
If your GT is a 96-98, I would look into doing a PI swap consisting of 99-04 heads, cams and aftermarket plenum/TB. You'll get a much bigger HP gain here, vs just swapping in two cams on a stock GT