I bought Stolspeed vortex generators a few weeks ago.
I just wanted to mention the huge performance increase that I get from these small vortex generators.
I know they are not for certified aircraft but in my country it does not matter.
I did install them on my 172 and I got no stall break anymore.
The aircraft is descending at 1000-1300ft/min but the nose does not drop, can fly a stable approach at 50kt and take off under 40.
I'm really happy with the product.
I'm in Paraguay,South america, I have a US commercial and instrument license.
We are flying kind of bush flying, that is where we appreciate the vortex generators.
Now we intend to apply your VGs to a 182 as well