We have had some problems with the 1. Generation RB25 (with external coildrivers).
Seems like the spark dissappears over 14 psi boost, even lower on big turboed/hp engines.
Don`t know if it is the coildriver or coil that is the weak link, but most likely the coils.
HKS dli box did not help(as it does on the supra`s)
Generation 2 coils seems better, but probably not working with the external amps.