Well part of "experimental" is learning. Read up, research, study the aerodynamics of VG's. Then get universal VG kit. The VG's tend to be stick on double sided affairs. Then install them and flight test it. Then you can report to everyone what you found. You can always remove them, but the down side is possible paint damage.
BTW Indicated speeds are typically not super accurate especially near stall. There are some tricks and flight test procedures to minimize the error, GPS and trailing static cone. Most A/S error is from the static pressure side not the pitot.
What to expect? I am assuming this is a RV9? Never flew either but it does not really matter. However the -9 was designed to be a slower easier to fly airplanes already (not that an RV3/4/6/7/8/10/14 are hard to fly). Van is a smart guy and optimized the plane for the job. You are not likely going to improve on it much if any, I am guessing. You won't know unless you try, this the first paragraph about experimentation. If you just want to learn and see how they work, great. If you do it for some leap in performance, nope.
However I guarantee you will lose a little cruise and top speed. #1 Aerodynamic Rule - There is no free lunch.... There are trade offs. As said vary well above VG's are the control "boundary flow" and allow the wing to fly at slightly higher critical angle of attack (slower stall), and improve effectivity of flight control (aileron, rudder or elevator) at low speed. Typically VG magic is used on the wing, but look at your jets at SEA, VG's sprout off the tail area as well. Those are for low speed pitch and yaw control improvement.
If you have a problem with too much money I can give you my paypal account. I am accepting donations.