Actually only the throttle body, power coil (stator), and temp sensor were the only additional parts.
It did performed well when it was working. The problem was that the throttle body assembly wasn't robust enough to handle the day to day operations that careless operator had put the engines through. When anytime the throttle started acting up the only option was replacement. Robin finally just say for all future repairs we were convert the EX21 EFI back over to a carburetor setup.
I still a Robin which Subaru owns and makes the engines but I only see one on UTVs every so often and they are carburetor versions. The last 650 was a pain to start during the winter until I modified the choke vane. Robin/Subaru engines seems to be very good engines in general.
