Lowering the car will reduce its frontal area and adding some rake helps the air flow around the back of the car's "green house" so both of these are good ideas. Blocking of the grill prevents air flow thru the radiator and engine compartment, also good is to run some sort of air dam to keep the air from going under the car. With these mods and 3-350 hp you should be good for at least 150. Lots of details but you are off to a good start.
Rex