Yeah the spoiler comes off very easily, and the car would be perfectly driveable without it on, just look a little... Aveo.
OP is planning to buy a second spoiler and do the mods to that, though, so he has a fallback plan if things on the build go horribly wrong. At least, that's the reason I would do it that way, I guess I might be reading between the lines.
Reasons for a spoiler:
Looks
Economy
Handling
Looks are of course completely subjective, but I think the ones we have are really only accomplishing this.
Economy seems to come from getting the car as close as possible to a teardrop shape... not really convinced our spoiler does much of this job, but to the extent it does, extending it onwards and downwards would probably help. Tradeoff is adding mass costs economy... so you have to get a net benefit here, not just a plain "this shape is less drag" one.
Handling, from the little research I've done, seems to consist of pushing the car down to counter the tendancy to lift at high speeds.... and that at street speeds this isn't really an issue on any car, much less so a front wheel drive one. Our spoiler doesn't seem to exert any downforce anyway, and you can only get that at the cost of adding some drag, so handling and economy are at odds with each other.
Extending the spoiler along its current lines, or maybe curving downwards some, would maybe increase economy, while adding an upward flare at the end would hypothetically increase downforce, both of course would change the look, and we're back to taste for that.
How about a mod to decrease the dirt/water suction effect, though? I've seen wings that push air downward on several cars, and wondered if that would help. Also, seen some that are similar to our spoiler, but have vents in them that would push some air down into the rear space.
