What sizes are the resonator, muffler, and what diameter is the pipe? Is your car naturally aspirated, supercharged, or turbo? Do you have a cat or header?
A full exhaust 2.5" or larger with a header on a naturally aspirated car will sound raspy. There's just not enough displacement to sound nice and deep. You will have to tune for sound using different mufflers, resonators, and glasspacks to get a good sound, or install a turbo. Turbos are great mufflers.
If you don't have a cat, or have a high flow, that will make the rasp 2x worse.
Glasspacks are good and cheap ways to deepen your exhaust greatly. Throw a 12"-18" one somewhere on the pipe, it'll really roughen up the sound.
Resonators can help, but they often leave a hollow sound. Large resonators can make the note deep, but it sounds like a deep monotone bellow. I personally think they sound shitty on small 4 cylinders.
The bigger the resonator, glasspack, muffler the better it will change the sound. On round body resonators, glasspacks, or mufflers the diameter is just as if not more than important than their length. A 7" diameter resonator will much more effective than a 4" diameter one.