Vortex Generators offer a number of incremental performance improvements with no observable change to cruise speed.
A number of Bearhawk owners have installed Stolspeed VG's. These are sold in Australia and have a solid reputation.
Stolspeed VG's come with full instructions and are relatively easy to install. They made from clear plastic - polycarbonate, and use an adhesive tape (included) to attach to the wing. Cardboard templates are included to get the correct spacing. The package includes spares.
Installation would take one person approximately 1-2 hours. Many builders do some initial Phase One test flying before installing VG's to establish a baseline. Installing them during the Phase One testing in most jurisdictions allows the Certificate of Airworthiness to be issued without further testing. If installed at a later date, more testing may be required to satisfy regulations.
The VG's are installed along the upper leading edge of the wing. The VG's are spaced closer together near the wingtips to provide increased effect near the ailerons.
When testing the stallspeed after the installation of VG's, it's worth noting that having power ON during a stall also tends to decrease the stallspeed significantly.
The installation of VG's on the 4B Bearhawk showed a decrease in power-off stall speed of 4-6 KIAS for all flap settings. A negligible change in stall speed for power-on stall was observed at all flap settings. However aileron response was improved in all cases.
VG's under the horizontal stabilizer
Installing VG's underneath the horizontal stabilizer served to increase elevator response when the CG was forward of 14". However the effect was minimal and was the equivalent to moving the CG approximately 0.5 - 1.0" aft.