With a stock 2.8 engine, there isn't much to be gained by a 'tune'. With knock sensors, O2 sensors, etc, engines within the last 20 years or so are self-tuning, so to speak. There have been supercharger kits available for the V6. What you shouldn't do is install a "cold-air intake". Suspension on the other hand can be changed if you want it to handle better or like a lower stance. An engine swap is an advanced undertaking and shouldn't be attempted unless you have lots of time, money, and experience in that sort of thing.