Agreed! The 20mm Garage Line might (have been) the answer...
I first tried the No-Pistons basic spacer. It just raises the pedal assembly but is 'cheap' on Amazon. It's a very nicely made and well finished product. Definitely improved the pedal height placement and heel/toe, BUT - for me - was still too far away, laterally, from the brake pedal get consistent a blip with a comfortable foot roll. If you have big feet it may be just the right temperature porridge!
I recently got the Garage Line spacer with lateral adjustment to try. These now come in 30 mm thickness only. I called them to verify fitment on my 2017 FiST and they were very nice chaps on the phone. The 6061 billet aluminum is well milled and cleanly finished in black with their logo etched on. It's a bit tight to get the pedal assembly on with the amount of wiring harness slack but is otherwise easy to install. The lateral adjustment is great, but the 30 mm is
much too thick, as others have commented, especially for harder, track braking.
I've measured all the thicknesses and plan to take it to a local machine shop to mill down to about 18 mm total thickness, which means re-milling the slots also. I will post an update (and will let Garage Line know too!) if that is the ticket.
(After 17 years enjoying flogging an E36 M3 on road and track I was spoiled rotten by it's perfect - for me - pedal positioning... I adore most of my FiST, it's astonishingly good on twisty mountain roads and a blast on the track, but Ford really gave us sucky pedal spacing!... In the 90's I mastered twisting my leg almost 90 deg and doing a heel kick for the blip in Integras, but my legs can't do that anymore
!)