The original development kit used a 3071. But that was a little too small and boost was falling off high rpm. 1.7 bar at 7400rpm.
APR redesigned the kit, fully v-band, ext.gate, and I believe the production stage 3 kit will be using the 3076, but nothing confirmed as still in development.
Im getting the chance to test out a 35 as the motors fully built, and will be a interesting comparo to the 3076 in terms of spool and response.