My answer is, it looks good on a sporty car, but in terms of perfor -mance it really doesn't have that much of an impact, remember spoilers and wings are completely different.
Spoilers are generally closer to the body of the car and helps diffuse the air thus reducing the drag but even so, the results of this impact is minimal. So in short those Spoilers you see equipped on vehicles has no aerodynamic down force effects, so don't expect any advantage from it, it's more of a decoration than performance.
Wings on the other hand are mounted much higher up and does have an aerodyamic effect of creating a down force, but you'll only feel the effect if you push to a speed of at least 70mph lower than that then it won't be much of factor too, and even if you are running at high speed, it would only give you a disadvantage than advantage if you happen to equip only the wing, in order to make this modification effective you'll also need to pair it with a front, rear and side skirts. You may ask why, the wings alone produces downforce on the part where it is equipped, so imagine the rear of your car pressed down obviously the front of the vehicle will lift and of course can produce a bad running result, but if you happened to pair it with the right skirts you'd be experiencing a swift ride, the speed and stability would all be awesome, you'll be able drive the vehicle to its limit without even noticing it.
To cut this story short, if your aiming for improving your vehicle's performance, try getting a wing not a spoiler and pair it with the right set of skirts and nothing less, this things should come in as a set to get the best performance. other than that you'll just be wasting your money.
Supercars Car Spoiler