My stats are:

Webra-50GT
Stock Muffler
5% Nitro
Idlebar plug
APC 9x8
16.2K @ 75 deg and 1,500 ASL

I fly a Patriot ARF with the Webra and it has the fastest throttle response of any engine I have owned (besides Jett-50) in 25 yrs-

I do not guess speeds but a viper/Predator with the Webra 9x8 combo will lite your hair on fire if you are not used to fast planes

FYI the Rossi-45 with mini tuned pipe gives up 600 RPM's to the Webra with this combo but pulls the fun-fly props faster by 400 RPM's