the FBO system deletes the ballast resistor with a jumper wire so that takes that out of the discussion. the FBO requires 12 volts to the coil and is supplied with a Pertronix coil. with the ballast gone the coil will now get whatever voltage the charging system provides; at least mine did. now there's 14-15 volts to the coil. i check the dwell on boxes and usually it will be somewhere between 35-40+ degrees; depending on the box. the FBO box i used had 15 degrees dwell,.... . so, i called Don at FBO and asked about that and he explained it to me and the truth is most of the explanation blew over the top of my head; basically didn't understand it all. i got to thinking that a mopar kit used a 1.25 ohm ballast (vs none with FBO) and will run 6-7 volts at the coil with twice the dwell (orange box is around 36 degrees). is this a case where less dwell time is needed to compensate for twice the voltage? is the spark voltage the same to the plugs; just done differently? i don't know but another one of those more questions than answers thing. anyhow, the soft rev limiter worked well which is what i needed but the driving situation stifled me. maybe i'll re-visit this at a later time.