The front spoiler, keeping air out from under the car is effective from as low as 20MPH. Just sticking a barrier under the front of (almost) any car will decrease turn-in understeer If you go to SCCA events, you'll see lots of stuff like this in the Street Prepared Classes On of Porsche's big innovations in the last couple of years was to add inflatable front spoilers to it's cars. They can blow them up and drop the air passage under the car at speed, but deflate so they don't get tore up in parking lots
It makes a huge difference if you're looking for speed. Even the old time racers like legendary innovator (not cheater ) Smokey Yunick new the benefits of 'aero'. Check out his '57 pickup where he masked off every air catching orifice he could to gain the edge.
Read somewhere years ago that the taller blade type spoiler adds 90lbs down force at 100mph. Didn't see or don't remember what the low early spoiler did.
I read on this site that the factory 2nd gen rear spoilers put so much down force at 180mph it makes the cars squirrely at that speed, seems like drag cars benefit from long flat rear spoilers that clean the air disturbance, where auto-x likes the tall ones that add more down force, I guess it really depends on what you are doing. For street it makes sense to go with auto-x philosophy but what if you prefer the look of drag car spoilers, I say go for it do what you like make it yours...the cutout looks cool to me