Info on Dastek Uni Q

Hi guys,

Please excuse my lack of knowledge... but can anyone give me some more info on a Dastek unichip? How does it work and what the fudge does piggyback mean?

I was chatting to a buddy and he told me about it but nothing he said makes any sense... which leads me to believe that he might not know himself...

I would like to fit it to my e36 318i (m42), would it make any difference?

Thanks