I put vortex generators on the Piper Lance and it really does make a difference. When doing a flight review, trying to stall the plane is very difficult. I would say the stall speed is reduced at least 5-6 knots.
I had a stec 500 and decided to update my panel on a PA32R. I updated with a whole new panel - G500, 750, 650, etc. The only thing I kept was an upgrade to STEC 3100. What a mistake. I has been problems for 3 months with NO support from Stec. If you have a choice - stay with all garmin!!!