Look at summit or jegs for 50 state compliant components with CARB certification. Things you should be able to do are intake, free flowing exhaust, possibly a chip? upgraded coil, wires, plugs. The biggest thing is to make sure its in top running condition and keep a good oil change on it. Stay away from gimmicks like the "tornado" or other crap like that.
2003 Grand Caravan
Member Vanatics Van Club-Spfld, IL Member Florida Van Council Member Central Florida Vans,-Orlando, FL