Quote: euromodder
Placement and size will be critical to determine wether they reduce overall drag, as they add drag by themselves and by the vortexes they produce.
I found these small VG's on a website for small single and twin engine planes that are less obtrusive.
text:
Micro Vortex Generators are small aluminum blades placed in a spanwise line aft of the leading edge of the wing and tail surfaces. They control airflow over the upper surface of the wing by creating vortices that energize the boundary layer. This results in improved performance and control authority at low airspeeds and high angles of attack.
Micro Vortex Generators - Over 500 Models of Aircraft Certified