Hey there sorry it took me so long to see the mention. I personally have been using Ephedrine for its actual pharmaceutical purpose, and just stacked it with the CY from Dexaprine XR to get the additional benefits. I took Kaizen Ephedrine which was 8mg per, and I would take 3 of them for 24mg 2 - 3 times per day along with one cap of Dexaprine XR. From what I understand this is only passable with the current version of Dexaprine XR as the original Dexaprine was much too potent to stack with Ephedrine. I too have a high stim tolerance, and this gave me very solid energy throughout the day.
I did avoid taking any excess caffeine though, so as to not overstimulate myself. I knew a guy that did the same thing as me but continued to take a pre-workout laden with stimulants. It didn't work out well for him though, as he's now on blood pressure medication. So I can't recommend that you overdo it, but I can say that I had great results with 24mg + 1 Dex XR 2 - 3 times per day.