i have ran a Jx.21, Rb C5 and C6( both stock and modded) Plus 4, and the Nova FMS..and by far the Nova FMS really out dose them in every area..from smooth consistent idle, power from all over the place and run time...in a truggy we averaged 9 minutes to a tank..and have stretched it to a little over ten...and some do even better. Since i tried this engine in a truggy..the only other one i would use is the Plus 4....that is just my experience.