should I change gears or tranny???

The trans. swap is the most work and most expensive but will by far yield the best results. If you go the route of swapping gears you really don't want gears taller than 3.54's and it still have decent take off with a load. The A518 came out in 91 if I remember right and in 96 it went to full electronic shift so you need one made between 91 and 95 or you'll have to wire in a trans. computer to make it work. The only big problem going with a A518 is the cost. You'll probably be lucky to buy one, rebuild it and install it for under a grand. If you plan on doing a lot of driving you'll save it in fuel but if you only drive it once in a while it'll take quite a while to even get your $1000 back.