Similar results on two DD dyno's. All to be found in the RB20 >260rwkw thread from several years ago.
RB2.1 HKS cast manifold, GT3040, cams from memory 260 deg, stock valves, ports tidied up, port matching.
http://www.skylinesaustralia.com/forums/topic/58229-top-rb20-club-do-you-have-over-260rwkw/page__view__findpost__p__3128732
Post with actual mods
If you scroll back a page there is another dyno print out with a high AT reading (correction??) but you get the idea.