I forgot to mention that knock sensors were employed largely to allow for more aggressive timing. By installing them, you give the ECU a means to monitor and back out timing when fuel is insufficient to run w/o knock (pinging). Moreover, you allow for a more aggressive timing curve since the knock sensors provide that safety net. It seems hard to believe an ECM w/o knock sensors is more aggressive than a system with them!

You sound like you'd know that.

That's why I have to wonder why cam, gearing, exhaust or some other physical configuration would account for the difference in dyno numbers.