I only have a more or less defined four pack, what do you do, diet, excesices, etc?

Well same problem, but my friend said me to use right diet

You're not going to get a sixpack unless you actually lower your body fat percentage. That's all their is to it...I've seen fat people go to 7% bodyfat and have killer 8 pack abs just because being fat slapped on a whole lot of muscle. All in all to get 6 pack abs you need to lower your bodyfat percentage. It also has to dow tih genetics, some people just can't get a 6 pack. Arnold had that. His genetics wouldn't let him have a 6 pack.