what trans are you useing . i have been chasing the same on mine . i found that today the futaba 9650 servo is the fix for mine. my set up it the logictech 2100t with the 9650. had a hs 81 on it before. in norm rate mode tail held fine . but as soon as i turn on hh it wants to wag. i have the newest tail stuff . just like trex 600 tail. is super smooth but no maker what i try on the 450 it wants to wag. so today i put a 9650 on it and it is al gone. hope this helps . still want to knwo your setup . to make sure your setting are right.