Crashburn69, I also agree that an 11-4 would do the job, but carefull throttle management is needed. An 11-4 is pretty thin for the TT, unless you restrict full throttle use to take-off & the up-lines only -- an Avistar wearing a TT .46 Pro with an 11-4 will dissapear straight up faster than most trainers can fly on the level. An 11-5 is a good choice for that combination & an 11-6 is also good -- they will both hover an Avistar without the risk of overreving on the level.