how low should i lower my car
 

i am lowering ym car i dont know if i should go 1.2 or 1.5

That would depend on what size wheels and tires your wanting to put on and what width, in case you want a wider look.

Aftermarket wheels and tire places can tell you exactly what will fit your car. You also have to be carefull that you are still able to turn your front wheels for whatever wheels and tires your going to use, so you don't rub your wheel wells or suspension components.

A little OT, but there is a guy in my development that has a lowered Golf/Rabbit and its so low, he cannot really pull into the drive without bottoming out and when he turns all you hears is rub. Everytime I see him leaving I just shake my head and laugh.