Basically tune the Customer EQ to look like a Ditch, Low frequencies load them up high, not too much though, mids low to medium, then the treble which is the far right, load that up a lil high, but not higher then the bass.
If you dont have a graphic EQ.
Then if you want bass
Bass +4
Treble +2
Mid +2
The best place to play with bass is on the amp, some will say dont turn up the gain, but as i listen to RnB aswell, nothing like some bass kickin' in..
So turn the gain up just a lil bit on the amp, and make sure the HPF is on so the subs arent playing vocals and are just thumping low end frequency bass.
What else do you have in your system? Splits .. Coaxials ??
To tell you the truth, you need a very fine ear to tune a car system properly, and im just giving you a basic guide, trial and error play around with the settings. Coz you can always reset them if you screw it up..
If you really cant go through the head ache, then just take it to a car audio place, they'll tune it perfectly
MRXTCZ