If he went to a larger venturi would that help, or are the kits that MSA sell inappropriately sprung, if that's a word? I face the same issue going forward on my rig. N42 is the most widely regarded cylinder head for enhancing performance but many "L SERIES" builders have had success with other cylinder heads, i.e. P90, E88,E34,etc. From the reading I have done it seems to be necessary to figure the flow, and combustion characteristics of the different heads then add in several other factors. It would be nice if tuning components were plug and play but some parts work better when tuned finely. I have spoken with several DATSUN SPECIALISTS over the years including those who raced on the SCCA circuit and always got varying opinions. When I am ready to put mine together I will consult the builder, tell him what I have and assess in theory what type of HP will I have. A good acquaintance once said never to go higher than a Stage 2 cam, but a builder in Austrailia can build a track engine that will tow all your race gear to the track! Go figure. So do your own science and it will probably not turn out to be plug and play. But a finely tuned "L" engine can get the job done.