beefing up my 318???

I got a 318 in my duster and it's a pretty slow car, i guess im used to driving cars alot faster so it feels even more slow to me. What are some upgrades i can do to increase power but not decrease my bank account very much, any help would be appreciated. The car has a cam in it but im not sure the specs the owner i got the car from didnt know very much about, he said the car could use a tune since the engine was just rebuilt, is this possible as to why i may think the car is kinda sluggish??? Thanks