How to lower my ride? Please help a newbie.

[los-lowrider]

Hi, I hope some of you can give me some advices how to lower my PU.
I know that here are several topics about lowering but I don't know if this set-up's will work on my pu.
My first idea was to lower with an air ride system from airride technologies, but the costs are very high.
So I don't know if a normal lowering won't work also.
I don't want to channel the frame. So how low can I go and what set up would you specialists advice me?
I enclose a picture of my pu.
Thank you.
I am very thankful for any advice or tip. I am from Germany so it isn't easy for me to get a tip from people who know what they are talkin about.