Mini V reliability and upgrades

Myself and a few friends have bought some mini Vs'

They are all totally different in handling and speed.

we have all set the props down low but 2 seem to cavitate badly.


is there a quick fix for the universal joints? we have resorted to superglueing them on because the grub screws are terrible


heres a picture of my 2, yellow one is very fast and handles well. white one seems to struggle for RPM and is probably about 2 mph slower. only thing ive done is regrease the shafts and remove the white nylon spacers as i felt they were making the shaft bind on both boats


http://img705.imageshack.us/img705/5874/bla001.jpg