First off, generally measured the front of the car and cut some 3/8 plywood to that dimension, then dummied it up, under the car....

Made dot-marks 3.5 inches from the front air dam...

and connected the dots...

I also did the same under the car, in retrospect, I should have made several small access holes instead of one big one..but maybe next time..

acquired some fasteners from the local hardware store, the "Captured nuts" are the most important since access is not easy in some places

Painted the splitter with truck bed liner since this was the most bulletproof and weather proof stuff I could think of at the time..

Installed it under the car using existing holes in the radiator support and then carefully...(except maybe in one spot-oops) drilling the air dam lip to accommodate the "captured nuts"

I also installed a set of aluminum hood pins using rubber hose to set the hood height

Presto..Race-o done!
View from the top....


total investment in the low tech splitter, about 70 bucks, plywood, bed liner and hardware.