need advice

hey guys. i recently got an 02 dak slt reg. cab 3.9L v6. i was wondering if anyone could give me some ideas or advice on some mods i could do to the truck to make it better. keep in mind that i dont have much money to spend on the truck right now. all that i have in mind now is a flowmaster exhaust and i was thinking about either the 30 series delta flow or the 50 series. which one would be best. any advice would be greatly appreciated. thanks...