With the right plane the Fox MK IV/VI can keep up but from what I have observed over the last 4 years will not start nor not restart reliably
The Fora's and Nelson's do have the edge...not power or speed...just simple repeat-ability on store bought fuel and props
BTW in 2014 Henry Nelson did a new run of N36c engines...needing 50 pre orders...he eventually sold 90+ Big Block N.36c fast engines
many went to non competitors...they are out there ....but will cost a bit to get .... my 3 were $385 each and the one reamaining is not for sale