Post pics of ur roof spoiler
nope, if anything it decreases it, my car moves left to right a bit at high speeds when it's tilted up. when it's down it doesnt move as much. I drive with it tilted up all the time though, it looks coool.
Its just for looks, i dont think it affects the car in any way really. I havent felt any difference.
I actually ordered this one. I received it within 10 days, the quality is good and the paint is matched perfectly. Here are some quick shots 










