how low with 275/55r20 ?

[BP68]

hey all had a quick question.

I have a 06 extended cab with gm 20s 25/55r20 tires

I really want to lower it, but not sure I want to commit to cutting the frame for a c notch and a 4/6

Any one have pics of a 2/4 drop. With spindles and springs up front and shackles and hangers in rear, would it still ride close to factory?
And would my front tires rub ? If so what is tallest I can get away with, I don't like the look of really skinny sidewalls.

here is a pic of how it sits now with just a 2" hanger to level it.