I have done the grille block and actually blocked and smoothed the underside of the front bumper on my 94 SC1 Coupe. Still thinking about how to best run a belly pan under the front of the car.
The car has a non-functional factory wing on the trunklid. Will removing this be a big improvement? I was going to unbolt it and put duct tape over the holes to keep the water out.
So far doing all the front end work has really worked out for an increase in average. I want to keep this trend going.
On a side note. Has anyone noticed the Corvette 1968 up body style windshield wiper cover. My uncle's 68 has it, but never saw it in use until recently when one of my co-workers drove her '70 Vette into the office and it was raining. That cover is completely flush, even seals against the windshield, when it is dry out, but turn on the wipers and it pops up and the wipers come out. Very interesting idea to get those big bumpy wipers out of the way, definitely a go fast reason for doing it back then.
From what I heard those wipers covers were a major pain and broke down quite often.
It was a clever idea and added a little gee-wiz pazzaz to the car though.
As far as removing the 'spoiler', - go for it !
The only good thing it might do is look cool, but if you can see past that, it actually does quite a bit more harm than good.
( It causes quite a bit of drag, and it adds weight. )
I would suggest using black electrical tape to seal the holes instead of duct tape.
I tried duct tape once on my car and it tore up the paint and left a gooey mess as well. Also, black electrical tape is less visible.
What's the deal with those wheels? Are they really directional like in the picture? Do you think they might generate less turbulence spinning one way rather than the other? Just curious. That spoiler might be minor compared to those wheels chopping up air like a turbine :-)
A better way to seal those holes would be carriage bolts. Pick some up at the hardware store, smear in some silicone to seal, then put them in. When you put them in put a very very light pressure on the nut to pull the bolt down into the silicone a bit, then carefully wipe the area around the bolt to get loose silicone out. After the silicone cures for a few hours, tighten the bolts down to about 20 ft lbs. This should present a nice, rounded bubble to the world and put a permanent seal around the holes provided the bolts aren't removed. Any tape you use will weather and leak within a year. Make sure to use a good stainless carriage bolts, not cheap ones, or you will have to either keep cleaning them up or will have to deal with rusty bolts.
My bet is you'd see no difference with that spoiler on or off. It's too little and too far back in the stream. It's possible from it's location and size that it even helps.
A yarn test would give you a better idea. And you wouldn't need to remove it for part of the test, just tape the leading edge closed. Watch the yarn behind the spoiler for the most insight, both taped and untaped.
For filling the holes from unwanted hardware removed:
Well nuts. Also called a rubber expansion plug. Get them in hardware stores, in the fasteners department.
Go to a hardware store and look at one. Note that the rubber expands to fill the hole when you tighten the screw. I'd use a stainless screw, just to avoid the mess that comes from regular ones getting wet.
Currently getting +/- 50 mpg in fall weather. EPA is 31/39 so not too shabby. WAI, fuel cutoff switch, full belly pan, smooth wheel covers.