Ed - the in cowl setup will never balance out the additional power
my under 8 ounce setup with the c fpipe is not cheap -but the power increase is easily 25% over any in cowl setup -not 25% more rpm --25% more power.
if you have a 9 lb plane you may be very happy with vertical pull
and if 3D hanging and vertical pull forever isn't your bag - 10-11 lbs will be fine