Just wondering if anyone else is having a problem with the fuel tanks H9 puts in their kits.

I have 3 different H9 arf planes all .40 size all them have a problems with the tanks splitting on the necks where the seam is.
replacing all with seamless flex tanks.

Anyone suggest any other mods that need to be done to the ultra stick .40,cap 232 .40 or the aresti .40?