I've been a long time AIM customer since the Solo DL came out many years ago. And lately at my local member track, I had began to plateau my times at about 2:12-2:13's. After renting then buying a Garmin, I have dropped to mid 2:09's and now chasing 2:08's at the track after just a handful of weekends.
The Garmin is just that good.
You have to be willing to experiment by trying new lines, push your braking points, change your turn ins, and be willing to entirely blow past corners while you test things out. But the device will reward you with simple to digest recommendations and helpful coaching real time while you're on track.
Happy to answer any questions, but here's a good live recording from when a buddy and me drove the same car, with the Garmin turned on, and we recorded how the Garmin gave us different instruction based on our driving style.