These things do work, a stable airflow does reduce compression fronts coming back from the inlet valves closing etc
BUT...
You are talking about a ridiculously tiny improvement, Would you feel the difference driving? No way. Hell, you would get more performance by taking the spare tire out of the trunk!
I do like the sound of a 50hp decal though...

in fact I would like to buy two, 100hp just from a few decals is a bargain!!!
