Well being a 96 , the only option for tuning is a DHP Powertuner with open software. I'd start off with an intake and downpipe ( cheap , easy mods ) , swtich to a 180* thermostat , and autolite 605 or 104 copper plugs. This should put you about 15 horsepower over stock ( if done well)
After an intake/downpipe , you might be ok for that 3.4 ( me and another 96er one here were fine even without a tune ) but i'd invest in a tuner or drive up to St. Augustine as i'm the only person in the state who can tune a 96 riv (( not that its tricky , i'm just the only person with the right software) or at least that i know of. But if i were you i'd purchase the tuner yourself i can email you the bin file.
One thing you'll notice is when its hot , these cars aren't all that peppy , but when the temperature drops into the 50s and 40s these thing fly!
If you do exhaust , the only ones i've heard that i like are borla , magnaflow , and hooker sounds ok too. Interestingly enough too they are also three of the best flowing quiet mufflers out there.