The Miata's pedal arrangement was not ideal for heel and toe shifting, so I had to do something about it. I ended up just bending the gas pedal down and to the left. To bend it down I put a wood block beneath the top part and bent. To go left, I just pulled it over. It appears this is a common project.
I also lowered the clutch pedal using the available adjustment. This gives a little more legroom and makes the engagement better.