Hardest part: ~80kw, ~400v, lightweight bank. <5mi. range/KERS-like.
Haltech, MaxxECU, FuelTech are all developing for 8HP.
In 10 years, time attack hybrids will use this unit. Aftermarket can't afford to ignore the challenges it solves.
So, selling my Miata & buying one to play with on a bench.