also different carbs reacte differently when a pipe is used --and different size props change the entire picture .
On my ZDZ50 n full AMT pipe - it works bet with engine stating at over 7000rpm -preferrably 7400-8000rpm - the engine is very happy with that setup but swapping props to ones which load to 7500 on the ground - the power is not nearly as good at hover -
pipes are not just another bolt on item which can be used without further adjustment
Done right - used right - big power boost on any size two stroke.
On little engines like my Evolution 1.6 - the std pipe works perfectly with any prop --provided that prop runs easily over 8000rpm on the ground .
On larger ones -it is really best to get some help from someone who has used the combo you want to use -and that is really on a case by case basis --