My 46Fx can hover my EF Edge 540 profile at half half thotlle WITH the tower muffler and 30% Nitro, and APC 12.25x3.75.
That combo can pull out from hover any airplane at 4.5lbs. I know, i do it every weekend

That tuned pipe cost only 15$ and increase by 700RPM min the 46FX. I tached 12700RPM the APC 12.25x3.75
http://www2.towerhobbies.com/cgi-bin...?&I=LXJB16&P=0
Daniel