Is the engine 'seeing' a LONG intake tube at WOT?  In other words, when the TB is WOT the engine is seeing an intake tube length of 20" - 24" (from looking at the picture) due to the CEET tubing instead of 12" - 14" (from the rotor to the TB).  If the intake is functioning as LONG then the engine will not rev.  Rotaries are sensitive to intake length.  Try a flight with only the TB and air horns. 

Hi Ken,

I've certainly proven that the engine doesn't like all the extra tubing.  I suspect it's more a matter of the small size, and turbulent nature of the SCEET tubing more than the length.  Either way, it's outa here.  The last test I posted was a flight with the TB and airhorns opened to the inside of the cowl, and it was much more powerful than with all the plumbing hooked up.   

I'm still considering what to do for the next scoop, and I might just put some hours on the plane this weekend with the TB open to the inside of the cowl while I decide. 

I really think the best performance option will probably be to build an airbox that seals to the top cowl, then add a scoop on top that feeds the box.  Trying to feed the intake with the radiator duct creates so many tight turns, and restrictions that it can never be ideal.  Also, the new monster prop is probably not doing me any favors with airflow in the area of the normal RV cowl inlets.  Fortunately, I still have plenty of water cooling, so it could be worse.