I am not sure what the validity of it is or if I was even understanding correctly but I was told that the turbo motors were less desirable in a race application because the lag/boost was tough to predict in the corners and they were able to tune these ACE motors up around 115hp naturally aspirated for a smooth powerband. You can get a Spark for less than what many people are paying for an aftermarket engine/exhaust/carb setup cost and easily tune it over 100hp through the ECU.
Aside from that, we had a handfull of Sparks at our ride this weekend and the guys seemed to like them, many guys were beating them up, beaching them at high speeds, hitting the double up and throwing them around without issues. I saw more Sparks do 180 stabs than Blasters.
This guy was testing the steering recall, it held up.